Articoli di riviste: "Amino acids sensing"

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Tang, Lei. "Sensing proteinogenic amino acids". Nature Methods 17, n. 2 (febbraio 2020): 126. http://dx.doi.org/10.1038/s41592-020-0741-z.

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Poulsen, P., B. Wu, R. F. Gaber, Kim Ottow, H. A. Andersen e M. C. Kielland-Brandt. "Amino acid sensing by Ssy1". Biochemical Society Transactions 33, n. 1 (1 febbraio 2005): 261–64. http://dx.doi.org/10.1042/bst0330261.

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Saccharomyces cerevisiae senses extracellular amino acids using two members of the family of amino acid transporters, Gap1 or Ssy1; aspects of the latter are reviewed here. Despite resemblance with bona fide transporters, Ssy1 appears unable to facilitate transport. Exposure of yeast to amino acids results in Ssy1-dependent transcriptional induction of several genes, in particular some encoding amino acid transporters. Amino acids differ strongly in their potency, leucine being the most potent one known. Using a selection system in which potassium uptake was made dependent on amino acid signalling, our laboratory has obtained and described gain-of-function mutations in SSY1. Some alleles conferred inducer-independent signalling; others increased apparent affinity for inducers. These results revealed that amino acid transport is not required for signalling and support the notion that sensing by Ssy1 occurs via its direct interaction with extracellular amino acids. Current work includes development of quantitative assays of sensing. We use the finding by Per Ljungdahl's laboratory that the signal transduction from Ssy1 involves proteolytic removal of an inhibitory part of the transcriptional activator Stp1. Protein-A Z-domain fused to the C-terminus of Stp1 and Western analysis using antibody against horseradish peroxidase allow quantification of sensing.

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Ray, L. B. "Sensing amino acids at the lysosome". Science 347, n. 6218 (8 gennaio 2015): 141–43. http://dx.doi.org/10.1126/science.347.6218.141-p.

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Ray, L. Bryan. "Sensing Amino Acids at the Lysosome". Science Signaling 8, n. 359 (13 gennaio 2015): ec12-ec12. http://dx.doi.org/10.1126/scisignal.aaa6512.

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Zhou, Yanxiu, Bin Yu e Kalle Levon. "Potentiometric Sensing of Chiral Amino Acids". Chemistry of Materials 15, n. 14 (luglio 2003): 2774–79. http://dx.doi.org/10.1021/cm030060e.

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Conigrave, A. D., H. C. Mun e S. C. Brennan. "Physiological significance of L-amino acid sensing by extracellular Ca2+-sensing receptors". Biochemical Society Transactions 35, n. 5 (25 ottobre 2007): 1195–98. http://dx.doi.org/10.1042/bst0351195.

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The calcium-sensing receptor is a multimodal, multimetabolic sensor that mediates the feedback-dependent control of whole body calcium metabolism. Remarkably, in addition to its role in Ca2+o (extracellular Ca2+) sensing, the CaR (Ca2+-sensing receptor) also responds to L-amino acids. L-amino acids appear to activate, predominantly, a signalling pathway coupled with intracellular Ca2+ mobilization, require a threshold concentration of Ca2+o for efficacy and sensitize the receptor to activation by Ca2+o. Here, we review the evidence that the CaR, like other closely related members of the class 3 GPCR (G-protein-coupled receptor) family including GPRC6A, is a broad-spectrum amino acid-sensing receptor, consider the nature of the signalling response to amino acids and discuss its physiological significance.

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Lynch, Ciarán C., Zeus A. De los Santos e Christian Wolf. "Chiroptical sensing of unprotected amino acids, hydroxy acids, amino alcohols, amines and carboxylic acids with metal salts". Chemical Communications 55, n. 44 (2019): 6297–300. http://dx.doi.org/10.1039/c9cc02525a.

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Optical chirality sensing of unprotected amino acids, hydroxy acids, amino alcohols, amines and carboxylic acids based on a practical mix-and-measure protocol with readily available copper, iron, palladium, manganese, cerium or rhodium salts is demonstrated.

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Lushchak, Oleh. "Amino Acids: Sensing and Implication into Aging". Journal of Vasyl Stefanyk Precarpathian National University 2, n. 1 (30 aprile 2015): 51–60. http://dx.doi.org/10.15330/jpnu.2.1.51-60.

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An ability to sense and respond to nutrient availability is an important requisite for life.Nutrient limitation is among main factors to influence the evolution of most cellular processes.Different pathways that sense intracellular and extracellular levels of carbohydtrates, amino acids,lipids, and intermediate metabolites are integrated and coordinated at the organismal levelthrough neuronal and humoral signals. During food abundance, nutrient-sensing pathwaysengage anabolism and storage, whereas limitation triggers the mechanisms, such as themobilization of internal stores including through autophagy. These processes are affected duringaging and are themselves important regulators of longevity, stress resistance, and age-relatedcomplications

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YAO, SHANG J., WEIJIAN XU, TERRI-LYNN DAY, JOHN F. PATZER e SIDNEY K. WOLFSON. "Interference of Glucose Sensing by Amino Acids". ASAIO Journal 40, n. 1 (gennaio 1994): 33–40. http://dx.doi.org/10.1097/00002480-199401000-00007.

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YAO, SHANG J., WEIJIAN XU, TERRI-LYNN DAY, JOHN F. PATZER e SIDNEY K. WOLFSON. "Interference of Glucose Sensing by Amino Acids". Asaio journal 40, SUPPLEMENT 1 (gennaio 1994): 33???40. http://dx.doi.org/10.1097/00002480-199401001-00007.

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Yao, Shang J., Weijian Xu, Terri-Lynn Day, John F. Patzer e Sidney K. Wolfson. "Interference of Glucose Sensing by Amino Acids". ASAIO Journal 40, n. 1 (gennaio 1994): 33–40. http://dx.doi.org/10.1097/00002480-199440010-00007.

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Shi, Wei-Nan, Fei Fan, Tian-Rui Zhang, Jia-Yue Liu, Xiang-Hui Wang e ShengJiang Chang. "Terahertz phase shift sensing and identification of a chiral amino acid based on a protein-modified metasurface through the isoelectric point and peptide bonding". Biomedical Optics Express 14, n. 3 (10 febbraio 2023): 1096. http://dx.doi.org/10.1364/boe.484181.

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The efficient sensing of amino acids, especially the distinction of their chiral enantiomers, is important for biological, chemical, and pharmaceutical research. In this work, a THz phase shift sensing method was performed for amino acid detection based on a polarization-dependent electromagnetically induced transparency (EIT) metasurface. More importantly, a method for binding the specific amino acids to the functional proteins modified on the metasurface was developed based on the isoelectric point theory so that the specific recognition for Arginine (Arg) was achieved among the four different amino acids. The results show that via high-Q phase shift, the detection precision for L-Arg is 2.5 × 10−5 g /ml, much higher than traditional sensing parameters. Due to the specific electrostatic adsorption by the functionalized metasurface to L-Arg, its detection sensitivity and precision are 22 times higher than the other amino acids. Furthermore, by comparing nonfunctionalized and functionalized metasurfaces, the D- and L-chiral enantiomers of Arg were distinguished due to their different binding abilities to the functionalized metasurface. Therefore, this EIT metasurface sensor and its specific binding method improve both detection precision and specificity in THz sensing for amino acids, and it will promote the development of THz highly sensitive detection of chiral enantiomers.

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Gaber, Richard F., Kim Ottow, Helge A. Andersen e Morten C. Kielland-Brandt. "Constitutive and Hyperresponsive Signaling by Mutant Forms of Saccharomyces cerevisiae Amino Acid Sensor Ssy1". Eukaryotic Cell 2, n. 5 (ottobre 2003): 922–29. http://dx.doi.org/10.1128/ec.2.5.922-929.2003.

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ABSTRACT Sensing of extracellular amino acids results in transcriptional induction of amino acid permease genes in yeast. Ssy1, a membrane protein resembling amino acid permeases, is required for signaling but is apparently unable to transport amino acids and is thus believed to be a sensor. By using a novel genetic screen in which potassium uptake was made dependent on amino acid signaling, we obtained gain-of-function mutations in SSY1. Some alleles confer inducer-independent signaling; others increase the apparent affinity for inducers. The results reveal that amino acid transport is not required for signaling and support the notion that sensing by Ssy1 occurs via its direct interaction with extracellular amino acids.

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Revanappa, Santhosh Kumar, Isha Soni, Manjappa Siddalinganahalli, Gururaj Kudur Jayaprakash, Roberto Flores-Moreno e Chandrashekar Bananakere Nanjegowda. "A Fukui Analysis of an Arginine-Modified Carbon Surface for the Electrochemical Sensing of Dopamine". Materials 15, n. 18 (13 settembre 2022): 6337. http://dx.doi.org/10.3390/ma15186337.

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Amino acid-modified carbon interfaces have huge applications in developing electrochemical sensing applications. Earlier reports suggested that the amine group of amino acids acted as an oxidation center at the amino acid-modified electrode interface. It was interesting to locate the oxidation centers of amino acids in the presence of guanidine. In the present work, we modeled the arginine-modified carbon interface and utilized frontier molecular orbitals and analytical Fukui functions based on the first principle study computations to analyze arginine-modified CPE (AMCPE) at a molecular level. The frontier molecular orbital and analytical Fukui results suggest that the guanidine (oxidation) and carboxylic acid (reduction) groups of arginine act as additional electron transfer sites on the AMCPE surface. To support the theoretical observations, we prepared the arginine-modified CPE (AMCPE) for the cyclic voltammetric sensing of dopamine (DA). The AMCPE showed excellent performance in detecting DA in blood serum samples.

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Dong, Jing, Xiao-Yao Dao, Xiao-Yu Zhang, Xiu-Du Zhang e Wei-Yin Sun. "Sensing Properties of NH2-MIL-101 Series for Specific Amino Acids via Turn-On Fluorescence". Molecules 26, n. 17 (2 settembre 2021): 5336. http://dx.doi.org/10.3390/molecules26175336.

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Metal–organic frameworks (MOFs) have been demonstrated to be desired candidates for sensing definite species owing to their tunable composition, framework structure and functionality. In this work, the NH2-MIL-101 series was utilized for sensing specific amino acids. The results show that cysteine (Cys) can significantly enhance the fluorescence emission of NH2-MIL-101-Fe suspended in water, while NH2-MIL-101-Al exhibits the ability to sense lysine (Lys), arginine (Arg) and histidine (His) in aqueous media via turn-on fluorescence emission. Titration experiments ensure that NH2-MIL-101-Fe and NH2-MIL-101-Al can selectively and quantitatively detect these amino acids. The sensing mechanism was examined and discussed. The results of this study show that the metal centers in MOFs are crucial for sensing specific amino acids.

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Mun, Hee-Chang, Alison H. Franks, Emma L. Culverston, Karen Krapcho, Edward F. Nemeth e Arthur D. Conigrave. "The Venus Fly Trap Domain of the Extracellular Ca2+-sensing Receptor Is Required for l-Amino Acid Sensing". Journal of Biological Chemistry 279, n. 50 (31 agosto 2004): 51739–44. http://dx.doi.org/10.1074/jbc.m406164200.

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We previously demonstrated that the human calcium-sensing receptor (CaR) is allosterically activated byl-amino acids (Conigrave, A. D., Quinn, S. J., and Brown, E. M. (2000)Proc. Natl. Acad. Sci. U. S. A.97, 4814–4819). However, the domain-based location of amino acid binding has been uncertain. We now show that the Venus Fly Trap (VFT) domain of CaR, but none of its other major domains, is required for amino acid sensing. Several constructs were informative when expressed in HEK293 cells. First, the wild-type CaR exhibited allosteric activation byl-amino acids as previously observed. Second, two CaR-mGlu chimeric receptor constructs that retained the VFT domain of CaR, one containing the extracellular Cys-rich region of CaR and the other containing the Cys-rich region of the rat metabotropic glutamate type-1 (mGlu-1) receptor, together with the rat mGlu-1 transmembrane region and C-terminal tail, retained amino acid sensing. Third, a CaR lacking residues 1–599 of the N-terminal extracellular head but retaining an intact CaR transmembrane region and a functional but truncated C terminus (headless-T903 CaR) failed to respond tol-amino acids but retained responsiveness to the type-II calcimimetic NPS R-467. Finally, a T903 CaR control that retained an intact N terminus also retainedl-amino acid sensing. Taken together, the data indicate that the VFT domain of CaR is necessary forl-amino acid sensing and are consistent with the hypothesis that the VFT domain is the site ofl-amino acid binding. The findings support the concept that the mGlu-1 amino acid binding site forl-glutamate is conserved as anl-amino acid binding site in its homolog, the CaR.

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Ljungdahl, Per O. "Amino-acid-induced signalling via the SPS-sensing pathway in yeast". Biochemical Society Transactions 37, n. 1 (20 gennaio 2009): 242–47. http://dx.doi.org/10.1042/bst0370242.

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Yeast cells rely on the SPS-sensing pathway to respond to extracellular amino acids. This nutrient-induced signal transduction pathway regulates gene expression by controlling the activity of two redundant transcription factors: Stp1 and Stp2. These factors are synthesized as latent cytoplasmic proteins with N-terminal regulatory domains. Upon induction by extracellular amino acids, the plasma membrane SPS-sensor catalyses an endoproteolytic processing event that cleaves away the regulatory N-terminal domains. The shorter forms of Stp1 and Stp2 efficiently target to the nucleus, where they bind and activate transcription of selected genes encoding a subset of amino acid permeases that function at the plasma membrane to catalyse the transport of amino acids into cells. In the present article, the current understanding of events in the SPS-sensing pathway that enable external amino acids to induce their own uptake are reviewed with a focus on two key issues: (i) the maintenance of Stp1 and Stp2 latency in the absence of amino acid induction; and (ii) the amino-acid-induced SPS-sensor-mediated proteolytic cleavage of Stp1 and Stp2.

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Wauson, Eric M., Andrés Lorente-Rodríguez e Melanie H. Cobb. "Minireview: Nutrient Sensing by G Protein-Coupled Receptors". Molecular Endocrinology 27, n. 8 (1 agosto 2013): 1188–97. http://dx.doi.org/10.1210/me.2013-1100.

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G protein-coupled receptors (GPCRs) are membrane proteins that recognize molecules in the extracellular milieu and transmit signals inside cells to regulate their behaviors. Ligands for many GPCRs are hormones or neurotransmitters that direct coordinated, stereotyped adaptive responses. Ligands for other GPCRs provide information to cells about the extracellular environment. Such information facilitates context-specific decision making that may be cell autonomous. Among ligands that are important for cellular decisions are amino acids, required for continued protein synthesis, as metabolic starting materials and energy sources. Amino acids are detected by a number of class C GPCRs. One cluster of amino acid-sensing class C GPCRs includes umami and sweet taste receptors, GPRC6A, and the calcium-sensing receptor. We have recently found that the umami taste receptor heterodimer T1R1/T1R3 is a sensor of amino acid availability that regulates the activity of the mammalian target of rapamycin. This review focuses on an array of findings on sensing amino acids and sweet molecules outside of neurons by this cluster of class C GPCRs and some of the physiologic processes regulated by them.

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Dato, Serena, Eneida Hoxha, Paolina Crocco, Francesca Iannone, Giuseppe Passarino e Giuseppina Rose. "Amino acids and amino acid sensing: implication for aging and diseases". Biogerontology 20, n. 1 (25 settembre 2018): 17–31. http://dx.doi.org/10.1007/s10522-018-9770-8.

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Pettiwala, Aafrin M., e Prabhat K. Singh. "Optical Sensors for Detection of Amino Acids". Current Medicinal Chemistry 25, n. 19 (30 maggio 2018): 2272–90. http://dx.doi.org/10.2174/0929867324666171106161410.

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Background: Amino acids are crucially involved in a myriad of biological processes. Any aberrant changes in physiological level of amino acids often manifest in common metabolic disorders, serious neurological conditions and cardiovascular diseases. Thus, devising methods for detection of trace amounts of amino acids becomes highly elemental to their efficient clinical diagnosis. Recently, the domain of developing optical sensors for detection of amino acids has witnessed significant activity which is the focus of the current review article. Methods: We undertook a detailed search of the peer-reviewed literature that primarily deals with optical sensors for amino acids and focuses on the use of different type of materials as a sensing platform. Results: Ninety-five papers have been included in the review, majority of which deal with optical sensors. We attempt to systematically classify these contributions based on the applications of various chemical and biological scaffolds such as polymers, supramolecular assemblies, nanoparticles, DNA, heparin etc for the sensing of amino acids. This review identifies that supramolecular assemblies and nanomaterial continue to be commonly used platforms to devise sensors for amino acids followed by surfactant assemblies. Conclusion: The broad implications of amino acids in human health and diagnosis have stirred a lot of interest to develop optimized optical detection systems for amino acids in recent years, using different materials based on chemical and biological scaffolds. We have also attempted to highlight the merits and demerits of some of the noteworthy sensor systems to instigate further efforts for constructing amino acids sensor based on unconventional concepts.

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Wang, Yu, Rashmi Chandra, Leigh Ann Samsa, Barry Gooch, Brian E. Fee, J. Michael Cook, Steven R. Vigna, Augustus O. Grant e Rodger A. Liddle. "Amino acids stimulate cholecystokinin release through the Ca2+-sensing receptor". American Journal of Physiology-Gastrointestinal and Liver Physiology 300, n. 4 (aprile 2011): G528—G537. http://dx.doi.org/10.1152/ajpgi.00387.2010.

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Cholecystokinin (CCK) is produced by discrete endocrine cells in the proximal small intestine and is released following the ingestion of food. CCK is the primary hormone responsible for gallbladder contraction and has potent effects on pancreatic secretion, gastric emptying, and satiety. In addition to fats, digested proteins and aromatic amino acids are major stimulants of CCK release. However, the cellular mechanism by which amino acids affect CCK secretion is unknown. The Ca2+-sensing receptor (CaSR) that was originally identified on parathyroid cells is not only sensitive to extracellular Ca2+ but is activated by extracellular aromatic amino acids. It has been postulated that this receptor may be involved in gastrointestinal hormone secretion. Using transgenic mice expressing a CCK promoter driven/enhanced green fluorescent protein (GFP) transgene, we have been able to identify and purify viable intestinal CCK cells. Intestinal mucosal CCK cells were enriched >200-fold by fluorescence-activated cell sorting. These cells were then used for real-time PCR identification of CaSR. Immunohistochemical staining with an antibody specific for CaSR confirmed colocalization of CaSR to CCK cells. In isolated CCK cells loaded with a Ca2+-sensitive dye, the amino acids phenylalanine and tryptophan, but not nonaromatic amino acids, caused an increase in intracellular Ca2+ ([Ca2+]i). The increase in [Ca2+]i was blocked by the CaSR inhibitor Calhex 231. Phenylalanine and tryptophan stimulated CCK release from intestinal CCK cells, and this stimulation was also blocked by CaSR inhibition. Electrophysiological recordings from isolated CCK-GFP cells revealed these cells to possess a predominant outwardly rectifying potassium current. Administration of phenylalanine inhibited basal K+ channel activity and caused CCK cell depolarization, consistent with changes necessary for hormone secretion. These findings indicate that amino acids have a direct effect on CCK cells to stimulate CCK release by activating CaSR and suggest that CaSR is the physiological mechanism through which amino acids regulate CCK secretion.

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Pradhan, Tuhin, Hyo Sung Jung, Joo Hee Jang, Tae Woo Kim, Chulhun Kang e Jong Seung Kim. "Chemical sensing of neurotransmitters". Chem. Soc. Rev. 43, n. 13 (2014): 4684–713. http://dx.doi.org/10.1039/c3cs60477b.

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This review focuses on the chemosensors for neurotransmitters published for the last 12 years, covering biogenic amines (dopamine, epinephrine, norepinephrine, serotonin, histamine and acetylcholine), amino acids (glutamate, aspartate, GABA, glycine and tyrosine), and adenosine.

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Lutt, Nanticha, e Jacob O. Brunkard. "Amino Acid Signaling for TOR in Eukaryotes: Sensors, Transducers, and a Sustainable Agricultural fuTORe". Biomolecules 12, n. 3 (2 marzo 2022): 387. http://dx.doi.org/10.3390/biom12030387.

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Eukaryotic cells monitor and regulate metabolism through the atypical protein kinase target of rapamycin (TOR) regulatory hub. TOR is activated by amino acids in animals and fungi through molecular signaling pathways that have been extensively defined in the past ten years. Very recently, several studies revealed that TOR is also acutely responsive to amino acid metabolism in plants, but the mechanisms of amino acid sensing are not yet established. In this review, we summarize these discoveries, emphasizing the diversity of amino acid sensors in human cells and highlighting pathways that are indirectly sensitive to amino acids, i.e., how TOR monitors changes in amino acid availability without a bona fide amino acid sensor. We then discuss the relevance of these model discoveries to plant biology. As plants can synthesize all proteinogenic amino acids from inorganic precursors, we focus on the possibility that TOR senses both organic metabolites and inorganic nutrients. We conclude that an evolutionary perspective on nutrient sensing by TOR benefits both agricultural and biomedical science, contributing to ongoing efforts to generate crops for a sustainable agricultural future.

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Silao, Fitz Gerald S., e Per O. Ljungdahl. "Amino Acid Sensing and Assimilation by the Fungal Pathogen Candida albicans in the Human Host". Pathogens 11, n. 1 (22 dicembre 2021): 5. http://dx.doi.org/10.3390/pathogens11010005.

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Nutrient uptake is essential for cellular life and the capacity to perceive extracellular nutrients is critical for coordinating their uptake and metabolism. Commensal fungal pathogens, e.g., Candida albicans, have evolved in close association with human hosts and are well-adapted to using diverse nutrients found in discrete host niches. Human cells that cannot synthesize all amino acids require the uptake of the “essential amino acids” to remain viable. Consistently, high levels of amino acids circulate in the blood. Host proteins are rich sources of amino acids but their use depends on proteases to cleave them into smaller peptides and free amino acids. C. albicans responds to extracellular amino acids by pleiotropically enhancing their uptake and derive energy from their catabolism to power opportunistic virulent growth. Studies using Saccharomyces cerevisiae have established paradigms to understand metabolic processes in C. albicans; however, fundamental differences exist. The advent of CRISPR/Cas9-based methods facilitate genetic analysis in C. albicans, and state-of-the-art molecular biological techniques are being applied to directly examine growth requirements in vivo and in situ in infected hosts. The combination of divergent approaches can illuminate the biological roles of individual cellular components. Here we discuss recent findings regarding nutrient sensing with a focus on amino acid uptake and metabolism, processes that underlie the virulence of C. albicans.

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Kordasht, Houman Kholafazad, Mohammad Hasanzadeh, Farzad Seidi e Parastoo Mohammad Alizadeh. "Poly (amino acids) towards sensing: Recent progress and challenges". TrAC Trends in Analytical Chemistry 140 (luglio 2021): 116279. http://dx.doi.org/10.1016/j.trac.2021.116279.

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Abdullah, Mahmud O., Run X. Zeng, Chelsea L. Margerum, David Papadopoli, Cian Monnin, Kaylee B. Punter, Charles Chu et al. "Mitochondrial hyperfusion via metabolic sensing of regulatory amino acids". Cell Reports 40, n. 7 (agosto 2022): 111198. http://dx.doi.org/10.1016/j.celrep.2022.111198.

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Smajilovic, Sanela, Petrine Wellendorph e Hans Brauner-Osborne. "Promiscuous Seven Transmembrane Receptors Sensing L-α-amino Acids". Current Pharmaceutical Design 20, n. 16 (31 maggio 2014): 2693–702. http://dx.doi.org/10.2174/13816128113199990576.

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Conigrave, Arthur D., Hee-Chang Mun e Hiu-Chuen Lok. "Aromatic l-Amino Acids Activate the Calcium-Sensing Receptor". Journal of Nutrition 137, n. 6 (1 giugno 2007): 1524S—1527S. http://dx.doi.org/10.1093/jn/137.6.1524s.

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Brennan, Sarah C., Thomas S. Davies, Martin Schepelmann e Daniela Riccardi. "Emerging roles of the extracellular calcium-sensing receptor in nutrient sensing: control of taste modulation and intestinal hormone secretion". British Journal of Nutrition 111, S1 (2 gennaio 2014): S16—S22. http://dx.doi.org/10.1017/s0007114513002250.

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The extracellular Ca-sensing receptor (CaSR) is a sensor for a number of key nutrients within the body, including Ca ions (Ca2+) and l-amino acids. The CaSR is expressed in a number of specialised cells within the gastrointestinal (GI) tract, and much work has been done to examine CaSR's role as a nutrient sensor in this system. This review article examines two emerging roles for the CaSR within the GI tract – as a mediator of kokumi taste modulation in taste cells and as a regulator of dietary hormone release in response to l-amino acids in the intestine.

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Meng, Delong, Qianmei Yang, Huanyu Wang, Chase H. Melick, Rishika Navlani, Anderson R. Frank e Jenna L. Jewell. "Glutamine and asparagine activate mTORC1 independently of Rag GTPases". Journal of Biological Chemistry 295, n. 10 (4 febbraio 2020): 2890–99. http://dx.doi.org/10.1074/jbc.ac119.011578.

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Nutrient sensing by cells is crucial, and when this sensing mechanism is disturbed, human disease can occur. mTOR complex 1 (mTORC1) senses amino acids to control cell growth, metabolism, and autophagy. Leucine, arginine, and methionine signal to mTORC1 through the well-characterized Rag GTPase signaling pathway. In contrast, glutamine activates mTORC1 through a Rag GTPase–independent mechanism that requires ADP-ribosylation factor 1 (Arf1). Here, using several biochemical and genetic approaches, we show that eight amino acids filter through the Rag GTPase pathway. Like glutamine, asparagine signals to mTORC1 through Arf1 in the absence of the Rag GTPases. Both the Rag-dependent and Rag-independent pathways required the lysosome and lysosomal function for mTORC1 activation. Our results show that mTORC1 is differentially regulated by amino acids through two distinct pathways.

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Feng, Haichao, Nan Zhang, Wenbin Du, Huihui Zhang, Yunpeng Liu, Ruixin Fu, Jiahui Shao, Guishan Zhang, Qirong Shen e Ruifu Zhang. "Identification of Chemotaxis Compounds in Root Exudates and Their Sensing Chemoreceptors in Plant-Growth-Promoting Rhizobacteria Bacillus amyloliquefaciens SQR9". Molecular Plant-Microbe Interactions® 31, n. 10 (ottobre 2018): 995–1005. http://dx.doi.org/10.1094/mpmi-01-18-0003-r.

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Chemotaxis-mediated response to root exudates, initiated by sensing-specific ligands through methyl-accepting chemotaxis proteins (MCP), is very important for root colonization and beneficial functions of plant-growth-promoting rhizobacteria (PGPR). Systematic identification of chemoattractants in complex root exudates and their sensing chemoreceptors in PGPR is helpful for enhancing their recruitment and colonization. In this study, 39 chemoattractants and 5 chemorepellents, including amino acids, organic acids, and sugars, were identified from 98 tested components of root exudates for the well-studied PGPR strain Bacillus amyloliquefaciens SQR9. Interestingly, mutant stain SQR9Δ8mcp, with all eight putative chemoreceptors completely deleted, lost the chemotactic responses to those 44 compounds. Gene complementation, chemotaxis assay, and isothermal titration calorimetry analysis revealed that McpA was mainly responsible for sensing organic acids and amino acids, while McpC was mostly for amino acids. These two chemoreceptors may play important roles in the rhizosphere chemotaxis of SQR9. In contrast, the B. amyloliquefaciens-unique chemoreceptor McpR was specifically responsible for arginine, and residues Tyr-78, Thr-131, and Asp-162 were critical for arginine binding. This study not only deepened our insights into PGPR–root interaction but also provided useful information to enhance the rhizosphere chemotaxis mobility and colonization of PGPR, which will promote their application in agricultural production.

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Liu, Chunchen, Linbao Ji, Jinhua Hu, Ying Zhao, Lee J. Johnston, Xiujun Zhang e Xi Ma. "Functional Amino Acids and Autophagy: Diverse Signal Transduction and Application". International Journal of Molecular Sciences 22, n. 21 (22 ottobre 2021): 11427. http://dx.doi.org/10.3390/ijms222111427.

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Functional amino acids provide great potential for treating autophagy-related diseases by regulating autophagy. The purpose of the autophagy process is to remove unwanted cellular contents and to recycle nutrients, which is controlled by many factors. Disordered autophagy has been reported to be associated with various diseases, such as cancer, neurodegeneration, aging, and obesity. Autophagy cannot be directly controlled and dynamic amino acid levels are sufficient to regulate autophagy. To date, arginine, leucine, glutamine, and methionine are widely reported functional amino acids that regulate autophagy. As a signal relay station, mammalian target of rapamycin complex 1 (mTORC1) turns various amino acid signals into autophagy signaling pathways for functional amino acids. Deficiency or supplementation of functional amino acids can immediately regulate autophagy and is associated with autophagy-related disease. This review summarizes the mechanisms currently involved in autophagy and amino acid sensing, diverse signal transduction among functional amino acids and autophagy, and the therapeutic appeal of amino acids to autophagy-related diseases. We aim to provide a comprehensive overview of the mechanisms of amino acid regulation of autophagy and the role of functional amino acids in clinical autophagy-related diseases and to further convert these mechanisms into feasible therapeutic applications.

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Bentley, Keith W., Yea G. Nam, Jaslynn M. Murphy e Christian Wolf. "Chirality Sensing of Amines, Diamines, Amino Acids, Amino Alcohols, and α-Hydroxy Acids with a Single Probe". Journal of the American Chemical Society 135, n. 48 (21 novembre 2013): 18052–55. http://dx.doi.org/10.1021/ja410428b.

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Zou, Jia-Ming, Qiang-Sheng Zhu, Hui Liang, Hai-Lin Lu, Xu-Fang Liang e Shan He. "Lysine Deprivation Regulates Npy Expression via GCN2 Signaling Pathway in Mandarin Fish (Siniperca chuatsi)". International Journal of Molecular Sciences 23, n. 12 (16 giugno 2022): 6727. http://dx.doi.org/10.3390/ijms23126727.

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Regulation of food intake is associated with nutrient-sensing systems and the expression of appetite neuropeptides. Nutrient-sensing systems generate the capacity to sense nutrient availability to maintain energy and metabolism homeostasis. Appetite neuropeptides are prominent factors that are essential for regulating the appetite to adapt energy status. However, the link between the expression of appetite neuropeptides and nutrient-sensing systems remains debatable in carnivorous fish. Here, with intracerebroventricular (ICV) administration of six essential amino acids (lysine, methionine, tryptophan, arginine, phenylalanine, or threonine) performed in mandarin fish (Siniperca chuatsi), we found that lysine and methionine are the feeding-stimulating amino acids other than the reported valine, and found a key appetite neuropeptide, neuropeptide Y (NPY), mainly contributes to the regulatory role of the essential amino acids on food intake. With the brain cells of mandarin fish cultured in essential amino acid deleted medium (lysine, methionine, histidine, valine, or leucine), we showed that only lysine deprivation activated the general control nonderepressible 2 (GCN2) signaling pathway, elevated α subunit of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation, increased activating transcription factor 4 (ATF4) protein expression, and finally induced transcription of npy. Furthermore, pharmacological inhibition of GCN2 and eIF2α phosphorylation signaling by GCN2iB or ISRIB, effectively blocked the transcriptional induction of npy in lysine deprivation. Overall, these findings could provide a better understanding of the GCN2 signaling pathway involved in food intake control by amino acids.

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Lee, Heather J., Hee-Chang Mun, Narelle C. Lewis, Michael F. Crouch, Emma L. Culverston, Rebecca S. Mason e Arthur D. Conigrave. "Allosteric activation of the extracellular Ca2+-sensing receptor by L-amino acids enhances ERK1/2 phosphorylation". Biochemical Journal 404, n. 1 (26 aprile 2007): 141–49. http://dx.doi.org/10.1042/bj20061826.

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The calcium-sensing receptor (CaR) mediates feedback control of Ca2+o (extracellular Ca2+) concentration. Although the mechanisms are not fully understood, the CaR couples to several important intracellular signalling enzymes, including PI-PLC (phosphoinositide-specific phospholipase C), leading to Ca2+i (intracellular Ca2+) mobilization, and ERK1/2 (extracellular-signal-regulated kinase 1/2). In addition to Ca2+o, the CaR is activated allosterically by several subclasses of L-amino acids, including the aromatics L-phenylalanine and L-tryptophan. These amino acids enhance the Ca2+o-sensitivity of Ca2+i mobilization in CaR-expressing HEK-293 (human embryonic kidney) cells and normal human parathyroid cells. Furthermore, on a background of a physiological fasting serum L-amino acid mixture, they induce a small, but physiologically significant, enhancement of Ca2+o-dependent suppression of PTH (parathyroid hormone) secretion. The impact of amino acids on CaR-stimulated ERK1/2, however, has not been determined. In the present study, we examined the effects of L-amino acids on Ca2+o-stimulated ERK1/2 phosphorylation as determined by Western blotting and a newly developed quantitative assay (SureFire). L-Amino acids induced a small, but significant, enhancement of Ca2+o-stimulated ERK1/2. In CaR-expressing HEK-293 cells, 10 mM L-phenylalanine lowered the EC50 for Ca2+o from approx. 2.3 to 2.0 mM in the Western blot assay and from 3.4 to 2.9 mM in the SureFire assay. The effect was stereoselective (L>D), and another aromatic amino acid, L-tryptophan, was also effective. The effects of amino acids were investigated further in HEK-293 cells that expressed the CaR mutant S169T. L-Phenylalanine normalized the EC50 for Ca2+o-stimulated Ca2+i mobilization from approx. 12 mM to 5.0 mM and ERK1/2 phosphorylation from approx. 4.6 mM to 2.6 mM. Taken together, the data indicate that L-phenylalanine and other amino acids enhance the Ca2+o-sensitivity of CaR-stimulated ERK1/2 phosphorylation; however, the effect is comparatively small and operates in the form of a fine-tuning mechanism.

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He, Fang, Chenlu Wu, Pan Li, Nengzhang Li, Dong Zhang, Quoqiang Zhu, Wenkai Ren e Yuanyi Peng. "Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation". BioMed Research International 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/9171905.

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Intestine is always exposed to external environment and intestinal microorganism; thus it is more sensitive to dysfunction and dysbiosis, leading to intestinal inflammation, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and diarrhea. An increasing number of studies indicate that dietary amino acids play significant roles in preventing and treating intestinal inflammation. The review aims to summarize the functions and signaling mechanisms of amino acids in intestinal inflammation. Amino acids, including essential amino acids (EAAs), conditionally essential amino acids (CEAAs), and nonessential amino acids (NEAAs), improve the functions of intestinal barrier and expressions of anti-inflammatory cytokines and tight junction proteins but decrease oxidative stress and the apoptosis of enterocytes as well as the expressions of proinflammatory cytokines in the intestinal inflammation. The functions of amino acids are associated with various signaling pathways, including mechanistic target of rapamycin (mTOR), inducible nitric oxide synthase (iNOS), calcium-sensing receptor (CaSR), nuclear factor-kappa-B (NF-κB), mitogen-activated protein kinase (MAPK), nuclear erythroid-related factor 2 (Nrf2), general controlled nonrepressed kinase 2 (GCN2), and angiotensin-converting enzyme 2 (ACE2).

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Wu, Zhihui, Jinghui Heng, Min Tian, Hanqing Song, Fang Chen, Wutai Guan e Shihai Zhang. "Amino acid transportation, sensing and signal transduction in the mammary gland: key molecular signalling pathways in the regulation of milk synthesis". Nutrition Research Reviews 33, n. 2 (10 marzo 2020): 287–97. http://dx.doi.org/10.1017/s0954422420000074.

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AbstractThe mammary gland, a unique exocrine organ, is responsible for milk synthesis in mammals. Neonatal growth and health are predominantly determined by quality and quantity of milk production. Amino acids are crucial maternal nutrients that are the building blocks for milk protein and are potential energy sources for neonates. Recent advances made regarding the mammary gland further demonstrate that some functional amino acids also regulate milk protein and fat synthesis through distinct intracellular and extracellular pathways. In the present study, we discuss recent advances in the role of amino acids (especially branched-chain amino acids, methionine, arginine and lysine) in the regulation of milk synthesis. The present review also addresses the crucial questions of how amino acids are transported, sensed and transduced in the mammary gland.

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Conigrave, Arthur D., e Edward M. Brown. "Taste Receptors in the Gastrointestinal Tract II.l-Amino acid sensing by calcium-sensing receptors: implications for GI physiology". American Journal of Physiology-Gastrointestinal and Liver Physiology 291, n. 5 (novembre 2006): G753—G761. http://dx.doi.org/10.1152/ajpgi.00189.2006.

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The extracellular calcium-sensing receptor (CaR) is a multimodal sensor for several key nutrients, notably Ca2+ions and l-amino acids, and is expressed abundantly throughout the gastrointestinal tract. While its role as a Ca2+ion sensor is well recognized, its physiological significance as an l-amino acid sensor and thus, in the gastrointestinal tract, as a sensor of protein ingestion is only now coming to light. This review focuses on the CaR’s amino acid sensing properties at both the molecular and cellular levels and considers new and putative physiological roles for the CaR in the amino acid-dependent regulation of gut hormone secretion, epithelial transport, and satiety.

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Ishida, Hikaru, Norihisa Yasui e Atsuko Yamashita. "Chemical range recognized by the ligand-binding domain in a representative amino acid-sensing taste receptor, T1r2a/T1r3, from medaka fish". PLOS ONE 19, n. 3 (22 marzo 2024): e0300981. http://dx.doi.org/10.1371/journal.pone.0300981.

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Taste receptor type 1 (T1r) proteins are responsible for recognizing nutrient chemicals in foods. In humans, T1r2/T1r3 and T1r1/T1r3 heterodimers serve as the sweet and umami receptors that recognize sugars or amino acids and nucleotides, respectively. T1rs are conserved among vertebrates, and T1r2a/T1r3 from medaka fish is currently the only member for which the structure of the ligand-binding domain (LBD) has been solved. T1r2a/T1r3 is an amino acid receptor that recognizes various l-amino acids in its LBD as observed with other T1rs exhibiting broad substrate specificities. Nevertheless, the range of chemicals that are recognized by T1r2a/T1r3LBD has not been extensively explored. In the present study, the binding of various chemicals to medaka T1r2a/T1r3LBD was analyzed. A binding assay for amino acid derivatives verified the specificity of this protein to l-α-amino acids and the importance of α-amino and carboxy groups for receptor recognition. The results further indicated the significance of the α-hydrogen for recognition as replacing it with a methyl group resulted in a substantially decreased affinity. The binding ability to the protein was not limited to proteinogenic amino acids, but also to non-proteinogenic amino acids, such as metabolic intermediates. Besides l-α-amino acids, no other chemicals showed significant binding to the protein. These results indicate that all of the common structural groups of α-amino acids and their geometry in the l-configuration are recognized by the protein, whereas a wide variety of α-substituents can be accommodated in the ligand binding sites of the LBDs.

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Yoon, Mee-Sup, Guangwei Du, Jonathan M. Backer, Michael A. Frohman e Jie Chen. "Class III PI-3-kinase activates phospholipase D in an amino acid–sensing mTORC1 pathway". Journal of Cell Biology 195, n. 3 (24 ottobre 2011): 435–47. http://dx.doi.org/10.1083/jcb.201107033.

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The rapamycin-sensitive mammalian target of rapamycin (mTOR) complex, mTORC1, regulates cell growth in response to mitogenic signals and amino acid availability. Phospholipase D (PLD) and its product, phosphatidic acid, have been established as mediators of mitogenic activation of mTORC1. In this study, we identify a novel role for PLD1 in an amino acid–sensing pathway. We find that amino acids activate PLD1 and that PLD1 is indispensable for amino acid activation of mTORC1. Activation of PLD1 by amino acids requires the class III phosphatidylinositol 3-kinase hVps34, which stimulates PLD1 activity through a functional interaction between phosphatidylinositol 3-phosphate and the Phox homology (PX) domain of PLD1. Furthermore, amino acids stimulate PLD1 translocation to the lysosomal region where mTORC1 activation occurs in an hVps34-dependent manner, and this translocation is necessary for mTORC1 activation. The PX domain is required for PLD1 translocation, mTORC1 activation, and cell size regulation. Finally, we show that the hVps34-PLD1 pathway acts independently of, and in parallel to, the Rag pathway in regulating amino acid activation of mTORC1.

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Kraidlova, Lucie, Griet Van Zeebroeck, Patrick Van Dijck e Hana Sychrová. "The Candida albicans GAP Gene Family Encodes Permeases Involved in General and Specific Amino Acid Uptake and Sensing". Eukaryotic Cell 10, n. 9 (15 luglio 2011): 1219–29. http://dx.doi.org/10.1128/ec.05026-11.

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ABSTRACTTheSaccharomyces cerevisiaegeneral amino acid permease Gap1 (ScGap1) not only mediates the uptake of most amino acids but also functions as a receptor for the activation of protein kinase A (PKA). Fungal pathogens can colonize different niches in the host, each containing various levels of different amino acids and sugars. TheCandida albicansgenome contains six genes homologous to theS. cerevisiae GAP1. The expression of these six genes inS. cerevisiaeshowed that the products of all sixC. albicansgenes differ in their transport capacities.C. albicansGap2 (CaGap2) is the true orthologue ofScGap1 as it transports all tested amino acids. The otherCaGap proteins have narrower substrate specificities thoughCaGap1 andCaGap6 transport several structurally unrelated amino acids.CaGap1,CaGap2, andCaGap6 also function as sensors. Upon detecting some amino acids, e.g., methionine, they are involved in a rapid activation of trehalase, a downstream target of PKA. Our data show thatCaGAPgenes can be functionally expressed inS. cerevisiaeand thatCaGap permeases communicate to the intracellular signal transduction pathway similarly toScGap1.

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Sriramulu, Dinesh Diraviam. "Amino Acids Enhance Adaptive Behaviour of Pseudomonas Aeruginosa in the Cystic Fibrosis Lung Environment". Microbiology Insights 3 (gennaio 2010): MBI.S4694. http://dx.doi.org/10.4137/mbi.s4694.

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Sputum of cystic fibrosis (CF) patients is a nutrient-rich environment. Higher amino acid content of CF sputum compared to normal sputum plays a major role in the CF-specific phenotype of P. aeruginosa. Presence of amino acids in the sputum-like environment influenced P. aeruginosa quorum-sensing activity and the formation of an unknown exopolysaccharide in the biofilm. Lipopolysaccharides isolated from P. aeruginosa grown in the presence of amino acids enhanced the release of cytokine IL-8 by human kidney and lung epithelial cells. The results of this study provide additional evidence on the role of amino acids towards adaptation of P. aeruginosa to the CF lung environment.

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Daly, Kristian, Miran Al-Rammahi, Andrew Moran, Marco Marcello, Yuzo Ninomiya e Soraya P. Shirazi-Beechey. "Sensing of amino acids by the gut-expressed taste receptor T1R1-T1R3 stimulates CCK secretion". American Journal of Physiology-Gastrointestinal and Liver Physiology 304, n. 3 (1 febbraio 2013): G271—G282. http://dx.doi.org/10.1152/ajpgi.00074.2012.

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CCK is secreted by endocrine cells of the proximal intestine in response to dietary components, including amino acids. CCK plays a variety of roles in digestive processes, including inhibition of food intake, consistent with a role in satiety. In the lingual epithelium, the sensing of a broad spectrum of l-amino acids is accomplished by the heteromeric amino acid (umami) taste receptor (T1R1-T1R3). T1R1 and T1R3 subunits are also expressed in the intestine. A defining characteristic of umami sensing by T1R1-T1R3 is its potentiation by IMP or GMP. Furthermore, T1R1-T1R3 is not activated by Trp. We show here that, in response to l-amino acids (Phe, Leu, Glu, and Trp), but not d-amino acids, STC-1 enteroendocrine cells and mouse proximal small intestinal tissue explants secrete CCK and that IMP enhances Phe-, Leu-, and Glu-induced, but not Trp-induced, CCK secretion. Furthermore, small interfering RNA inhibition of T1R1 expression in STC-1 cells results in significant diminution of Phe-, Leu-, and Glu-stimulated, but not Trp-stimulated, CCK release. In STC-1 cells and mouse intestine, gurmarin inhibits Phe-, Leu-, and Glu-induced, but not Trp-stimulated, CCK secretion. In contrast, the Ca2+-sensing receptor antagonist NPS2143 inhibits Phe-stimulated CCK release partially and Trp-induced CCK secretion totally in mouse intestine. However, NPS2143 has no effect on Leu- or Glu-induced CCK secretion. Collectively, our data demonstrate that functional characteristics and cellular location of the gut-expressed T1R1-T1R3 support its role as a luminal sensor for Phe-, Leu-, and Glu-induced CCK secretion.

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Hassan, Diandra S., Zeus A. De los Santos, Kimberly G. Brady, Steven Murkli, Lyle Isaacs e Christian Wolf. "Chiroptical sensing of amino acids, amines, amino alcohols, alcohols and terpenes with π-extended acyclic cucurbiturils". Organic & Biomolecular Chemistry 19, n. 19 (2021): 4248–53. http://dx.doi.org/10.1039/d1ob00345c.

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Wu, Boqian, Kim Ottow, Peter Poulsen, Richard F. Gaber, Eva Albers e Morten C. Kielland-Brandt. "Competitive intra- and extracellular nutrient sensing by the transporter homologue Ssy1p". Journal of Cell Biology 173, n. 3 (1 maggio 2006): 327–31. http://dx.doi.org/10.1083/jcb.200602089.

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Abstract (sommario):

Recent studies of Saccharomyces cerevisiae revealed sensors that detect extracellular amino acids (Ssy1p) or glucose (Snf3p and Rgt2p) and are evolutionarily related to the transporters of these nutrients. An intriguing question is whether the evolutionary transformation of transporters into nontransporting sensors reflects a homeostatic capability of transporter-like sensors that could not be easily attained by other types of sensors. We previously found SSY1 mutants with an increased basal level of signaling and increased apparent affinity to sensed extracellular amino acids. On this basis, we propose and test a general model for transporter- like sensors in which occupation of a single, central ligand binding site increases the activation energy needed for the conformational shift between an outward-facing, signaling conformation and an inward-facing, nonsignaling conformation. As predicted, intracellular leucine accumulation competitively inhibits sensing of extracellular amino acids. Thus, a single sensor allows the cell to respond to changes in nutrient availability through detection of the relative concentrations of intra- and extracellular ligand.

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Ratautė, Kristina, e Dalius Ratautas. "A Review from a Clinical Perspective: Recent Advances in Biosensors for the Detection of L-Amino Acids". Biosensors 14, n. 1 (22 dicembre 2023): 5. http://dx.doi.org/10.3390/bios14010005.

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The field of biosensors is filled with reports and designs of various sensors, with the vast majority focusing on glucose sensing. However, in addition to glucose, there are many other important analytes that are worth investigating as well. In particular, L-amino acids appear as important diagnostic markers for a number of conditions. However, the progress in L-amino acid detection and the development of biosensors for L-amino acids are still somewhat insufficient. In recent years, the need to determine L-amino acids from clinical samples has risen. More clinical data appear to demonstrate that abnormal concentrations of L-amino acids are related to various clinical conditions such as inherited metabolic disorders, dyslipidemia, type 2 diabetes, muscle damage, etc. However, to this day, the diagnostic potential of L-amino acids is not yet fully established. Most likely, this is because of the difficulties in measuring L-amino acids, especially in human blood. In this review article, we extensively investigate the ‘overlooked’ L-amino acids. We review typical levels of amino acids present in human blood and broadly survey the importance of L-amino acids in most common conditions which can be monitored or diagnosed from changes in L-amino acids present in human blood. We also provide an overview of recent biosensors for L-amino acid monitoring and their advantages and disadvantages, with some other alternative methods for L-amino acid quantification, and finally we outline future perspectives related to the development of biosensing devices for L-amino acid monitoring.

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Idrees, Muhammad, Afzal R. Mohammad, Nazira Karodia e Ayesha Rahman. "Multimodal Role of Amino Acids in Microbial Control and Drug Development". Antibiotics 9, n. 6 (17 giugno 2020): 330. http://dx.doi.org/10.3390/antibiotics9060330.

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Abstract (sommario):

Amino acids are ubiquitous vital biomolecules found in all kinds of living organisms including those in the microbial world. They are utilised as nutrients and control many biological functions in microorganisms such as cell division, cell wall formation, cell growth and metabolism, intermicrobial communication (quorum sensing), and microbial-host interactions. Amino acids in the form of enzymes also play a key role in enabling microbes to resist antimicrobial drugs. Antimicrobial resistance (AMR) and microbial biofilms are posing a great threat to the world’s human and animal population and are of prime concern to scientists and medical professionals. Although amino acids play an important role in the development of microbial resistance, they also offer a solution to the very same problem i.e., amino acids have been used to develop antimicrobial peptides as they are highly effective and less prone to microbial resistance. Other important applications of amino acids include their role as anti-biofilm agents, drug excipients, drug solubility enhancers, and drug adjuvants. This review aims to explore the emerging paradigm of amino acids as potential therapeutic moieties.

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HYDE, Russell, Peter M. TAYLOR e Harinder S. HUNDAL. "Amino acid transporters: roles in amino acid sensing and signalling in animal cells". Biochemical Journal 373, n. 1 (1 luglio 2003): 1–18. http://dx.doi.org/10.1042/bj20030405.

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Amino acid availability regulates cellular physiology by modulating gene expression and signal transduction pathways. However, although the signalling intermediates between nutrient availability and altered gene expression have become increasingly well documented, how eukaryotic cells sense the presence of either a nutritionally rich or deprived medium is still uncertain. From recent studies it appears that the intracellular amino acid pool size is particularly important in regulating translational effectors, thus, regulated transport of amino acids across the plasma membrane represents a means by which the cellular response to amino acids could be controlled. Furthermore, evidence from studies with transportable amino acid analogues has demonstrated that flux through amino acid transporters may act as an initiator of nutritional signalling. This evidence, coupled with the substrate selectivity and sensitivity to nutrient availability classically associated with amino acid transporters, plus the recent discovery of transporter-associated signalling proteins, demonstrates a potential role for nutrient transporters as initiators of cellular nutrient signalling. Here, we review the evidence supporting the idea that distinct amino acid “receptors” function to detect and transmit certain nutrient stimuli in higher eukaryotes. In particular, we focus on the role that amino acid transporters may play in the sensing of amino acid levels, both directly as initiators of nutrient signalling and indirectly as regulators of external amino acid access to intracellular receptor/signalling mechanisms.

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Fabbrizzi, Luigi, Maurizio Licchelli, Angelo Perotti, Antonio Poggi, Giuliano Rabaioli, Donatella Sacchi e Angelo Taglietti. "Fluorescent molecular sensing of amino acids bearing an aromatic residue". Journal of the Chemical Society, Perkin Transactions 2, n. 11 (20 settembre 2001): 2108–13. http://dx.doi.org/10.1039/b105480p.

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Oliveira-Brett, Ana Maria, Victor Constatin Diculescu, Teodor Adrian Enache, Isabel P. G. Fernandes, Ana-Maria Chiorcea-Paquim e S. Carlos B. Oliveira. "Bioelectrochemistry for sensing amino acids, peptides, proteins and DNA interactions". Current Opinion in Electrochemistry 14 (aprile 2019): 173–79. http://dx.doi.org/10.1016/j.coelec.2019.03.008.

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