Artykuły w czasopismach: „Gyr Operon”

1

Unniraman, Shyam, Monalisa Chatterji i Valakunja Nagaraja. "DNA Gyrase Genes in Mycobacterium tuberculosis: a Single Operon Driven by Multiple Promoters". Journal of Bacteriology 184, nr 19 (1.10.2002): 5449–56. http://dx.doi.org/10.1128/jb.184.19.5449-5456.2002.

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ABSTRACT The two genes encoding DNA gyrase in Mycobacterium tuberculosis are present next to each other in the genome, with gyrB upstream of gyrA. We show that the primary transcript is dicistronic. However, in addition to the principal promoter, there are multiple weaker promoters that appear to fine-tune transcription. With these and other mycobacterial promoters, we propose consensus promoter sequences for two distinct sigma factors. In addition to this, the gyr genes in M. tuberculosis, as in other species, are subject to autoregulation, albeit with slower kinetics, probably reflecting the slower metabolism of the organism.

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Jha, Rajiv Kumar, Priyanka Tare i Valakunja Nagaraja. "Regulation of the gyr operon of Mycobacterium tuberculosis by overlapping promoters, DNA topology, and reiterative transcription". Biochemical and Biophysical Research Communications 501, nr 4 (lipiec 2018): 877–84. http://dx.doi.org/10.1016/j.bbrc.2018.05.067.

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Liu, Yan-Jie, Biao Hu, Jia-Bi Zhu, Shan-Jiong Shen i Guan-Qiao Yu. "nifH Promoter Activity Is Regulated by DNA Supercoiling in Sinorhizobium meliloti". Acta Biochimica et Biophysica Sinica 37, nr 4 (1.04.2005): 221–26. http://dx.doi.org/10.1111/j.1745-7270.2005.00037.x.

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AbstractIn prokaryotes, DNA supercoiling regulates the expression of many genes; for example, the expression of Klebsiella pneumoniae nifLA operon depends on DNA negative supercoiling in anaerobically grown cells, which indicates that DNA supercoiling might play a role in gene regulation of the anaerobic response. Since the expression of the nifH promoter in Sinorhizobium meliloti is not repressed by oxygen, it is proposed that the status of DNA supercoiling may not affect the expression of the nifH promoter. We tested this hypothesis by analyzing nifH promoter activity in wild-type and gyr Escherichia coli in the presence and absence of DNA gyrase inhibitors. Our results show that gene expression driven by the S. meliloti nifH promoter requires the presence of active DNA gyrase. Because DNA gyrase increases the number of negative superhelical turns in DNA in the presence of ATP, our data indicate that negative supercoiling is also important for nifH promoter activity. Our study also shows that the DNA supercoiling-dependent S. meliloti nifH promoter activity is related to the trans-acting factors NtrC and NifA that activate it. DNA supercoiling appeared to have a stronger effect on NtrC-activated nifH promoter activity than on NifA-activated promoter activity. Collectively, these results from the S. meliloti nifH promoter model system seem to indicate that, in addition to regulating gene expression during anaerobic signaling, DNA supercoiling may also provide a favorable topology for trans-acting factor binding and promoter activation regardless of oxygen status.

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Hornstra, Luc M., Ynte P. de Vries, Marjon H. J. Wells-Bennik, Willem M. de Vos i Tjakko Abee. "Characterization of Germination Receptors of Bacillus cereus ATCC 14579". Applied and Environmental Microbiology 72, nr 1 (styczeń 2006): 44–53. http://dx.doi.org/10.1128/aem.72.1.44-53.2006.

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ABSTRACT Specific amino acids, purine ribonucleosides, or a combination of the two is required for efficient germination of endospores of Bacillus cereus ATCC 14579. A survey including 20 different amino acids showed that l-alanine, l-cysteine, l-threonine, and l-glutamine are capable of initiating the germination of endospores of B. cereus ATCC 14579. In addition, the purine ribonucleosides inosine and adenosine can trigger germination of the spores. Advanced annotation of the B. cereus ATCC 14579 genome revealed the presence of seven putative germination (ger) operons, termed gerG, gerI, gerK, gerL, gerQ, gerR, and gerS. To determine the role of the encoded putative receptors in nutrient-induced germination, disruption mutants were constructed by the insertion of pMUTIN4 into each of the seven operons. Four of the seven mutants were affected in the germination response to amino acids or purine ribonucleosides, whereas no phenotype could be attributed to the mutants with disrupted gerK, gerL, and gerS loci. The strain with a disrupted gerR operon was severely hampered in the ability to germinate: germination occurred in response to l-glutamine but not in the presence of any of the other amino acids tested. The gerG mutant showed significantly reduced l-glutamine-induced germination, which points to a role of this receptor in the l-glutamine germination signaling pathway. gerR, gerI, and gerQ mutants showed reduced germination rates in the presence of inosine, suggesting a role for these operons in ribonucleoside signaling. Efficient germination by the combination of l-glutamine and inosine was shown to involve the gerG and gerI operons, since the germination of mutants lacking either one of these receptors was significantly reduced. Germination triggered by the combination of l-phenylalanine and inosine was lost in the gerI mutant, indicating that both molecules are effective at the GerI receptor.

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Abdoarrahem, M. M., K. Gammon, B. N. Dancer i C. Berry. "Genetic Basis for Alkaline Activation of Germination in Bacillus thuringiensis subsp. israelensis". Applied and Environmental Microbiology 75, nr 19 (31.07.2009): 6410–13. http://dx.doi.org/10.1128/aem.00962-09.

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ABSTRACT Differences in activation between spores from strains of Bacillus thuringiensis subsp. israelensis with and without the toxin-encoding plasmid pBtoxis are demonstrated. Following alkaline activation, the strain bearing pBtoxis shows a significantly greater germination rate. Expression of just three genes constituting a previously identified, putative ger operon from this plasmid is sufficient to produce the same phenotype and characterizes this operon as a genetic determinant of alkaline activation.

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Hornstra, Luc M., Ynte P. de Vries, Willem M. de Vos, Tjakko Abee i Marjon H. J. Wells-Bennik. "gerR, a Novel ger Operon Involved in l-Alanine- and Inosine-Initiated Germination of Bacillus cereus ATCC 14579". Applied and Environmental Microbiology 71, nr 2 (luty 2005): 774–81. http://dx.doi.org/10.1128/aem.71.2.774-781.2005.

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ABSTRACT Bacillus cereus endospores germinate in response to particular nutrients. Spores are able to sense these nutrients in the environment by receptors encoded by the gerA family of operons. Analysis of the Bacillus cereus ATCC 14579 genome revealed seven gerA family homologues. Using a transposon Tn917-based insertional mutagenesis approach followed by an enrichment procedure to select for l-alanine-induced germination mutants, we isolated a mutant with a defect in the l-alanine germination pathway. The transposon disrupted the last gene of a tricistronic gerA family operon, designated gerR, with the order gerRA, gerRC, gerRB. A second mutant was created by insertion of pMUTIN4 in gerRC. Both mutants showed the same phenotype for nutrient-induced germination. Spores of the gerR mutant strains were blocked in their l-alanine-initiated germination pathway and showed a delayed inosine-induced germination response. Apparently, germination mediated by l-alanine and inosine cannot be compensated for completely by the other germinant receptors, and this points towards an essential role of the gerR-encoded receptor in the receptor complex. In food products, spores of the mutant strains showed a reduced germination response compared to spores of the parental strain. High-pressure-initiated germination was not affected by the gerR mutations, as experiments with 100 and 550 MPa showed no difference with spores of the parental strain.

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7

Wiame, Elsa, Pedro Lamosa, Helena Santos i Emile Van Schaftingen. "Identification of glucoselysine-6-phosphate deglycase, an enzyme involved in the metabolism of the fructation product glucoselysine". Biochemical Journal 392, nr 2 (22.11.2005): 263–69. http://dx.doi.org/10.1042/bj20051183.

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The metabolism of the glycation product fructose-ϵ-lysine in Escherichia coli involves its ATP-dependent phosphorylation by a specific kinase (FrlD), followed by the conversion of fructoselysine 6-phosphate into glucose 6-phosphate and lysine by fructoselysine-6-phosphate deglycase (FrlB), which is distantly related to the isomerase domain of glucosamine-6-phosphate synthase. As shown in the present work, several bacterial operons comprise: (1) a homologue of fructoselysine-6-phosphate deglycase; (2) a second homologue of the isomerase domain of glucosamine-6-phosphate synthase, more closely related to it; and (3) components of a novel phosphotransferase system, but no FrlD homologue. The FrlB homologue (GfrF) and the closer glucosamine-6-phosphate synthase homologue (GfrE) encoded by an Enterococcus faecium operon were expressed in E. coli and purified. Similar to FrlB, GfrF catalysed the reversible conversion of fructoselysine 6-phosphate into glucose 6-phosphate and lysine. When incubated with fructose 6-phosphate and elevated concentrations of lysine, GfrE catalysed the formation of a compound identified as 2-ϵ-lysino-2-deoxy-6-phospho-glucose (glucoselysine 6-phosphate) by NMR. GfrE also catalysed the reciprocal conversion, i.e. the formation of fructose 6-phosphate (but not glucose 6-phosphate) from glucoselysine 6-phosphate. The equilibrium constant of this reaction (0.8 M) suggests that the enzyme serves to degrade glucoselysine 6-phosphate. In conclusion, GfrF and GfrE serve to metabolize glycation products formed from lysine and glucose (fructoselysine) or fructose (glucoselysine), via their 6-phospho derivatives. The latter are presumably formed by the putative phosphotransferase system encoded by gfrA–gfrD. The designation gfr (glycation and fructation product degradation) is proposed for this operon. This is the first description of an enzyme participating in the metabolism of fructation products.

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8

Dolgushev, Vasily, i Thomas Willwacher. "A direct computation of the cohomology of the braces operad". Forum Mathematicum 29, nr 2 (1.03.2017): 465–88. http://dx.doi.org/10.1515/forum-2016-0123.

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Sleator, Roy D., Cormac G. M. Gahan i Colin Hill. "Identification and Disruption of theproBA Locus in Listeria monocytogenes: Role of Proline Biosynthesis in Salt Tolerance and Murine Infection". Applied and Environmental Microbiology 67, nr 6 (1.06.2001): 2571–77. http://dx.doi.org/10.1128/aem.67.6.2571-2577.2001.

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ABSTRACT Intracellular accumulation of the amino acid proline has previously been linked to the salt tolerance and virulence potential of a number of bacteria. Taking advantage of the proBA mutantEscherichia coli CSH26, we identified a listerialproBA operon coding for enzymes functionally similar to the glutamyl kinase (GK) and glutamylphosphate reductase (GPR) enzyme complex which catalyzes the first and second steps of proline biosynthesis in E. coli. The first gene of the operon,proB, is predicted to encode GK, a 276-residue protein with a calculated molecular mass of 30.03 kDa and pl of 5.2. Distal to the promoter and overlapping the 3′ end of proB by 17 bp isproA, which encodes GPR, a 415-residue protein with a calculated molecular mass of 45.50 kDa (pl 5.3). Using this information, we created a chromosomal deletion mutant by allelic exchange which is auxotrophic for proline. This mutant was used to assess the contribution of proline anabolism to osmotolerance and virulence. While inactivation of proBA had no significant effect on virulence in mouse assays (either perorally or intraperitoneally), growth at low (2 to 4% NaCl) and high (>6% NaCl) salt concentrations in complex media was significantly reduced in the absence of efficient proline synthesis. We conclude that while proline biosynthesis plays little, if any, role in the intracellular life cycle and infectious nature of Listeria monocytogenes, it can play an important role in survival in osmolyte-depleted environments of elevated osmolarity.

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10

Hornstra, Luc M., Ynte P. de Vries, Willem M. de Vos i Tjakko Abee. "Influence of Sporulation Medium Composition on Transcription of ger Operons and the Germination Response of Spores of Bacillus cereus ATCC 14579". Applied and Environmental Microbiology 72, nr 5 (maj 2006): 3746–49. http://dx.doi.org/10.1128/aem.72.5.3746-3749.2006.

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ABSTRACT Bacillus cereus ATCC 14579 endospores were produced in Y1 medium, a nutrient-rich, chemically defined sporulation medium, and in modified G medium, containing low amounts of nutrients. The average transcription level of the seven ger operons per cell was 3.5 times higher in Y1 medium, and the spores grown in this medium showed an enhanced germination response.

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Zheng, Yu, Joseph D. Szustakowski, Lance Fortnow, Richard J. Roberts i Simon Kasif. "Computational Identification of Operons in Microbial Genomes". Genome Research 12, nr 8 (15.10.2001): 1221–30. http://dx.doi.org/10.1101/gr.200602.

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12

Price, M. N. "Operon formation is driven by co-regulation and not by horizontal gene transfer". Genome Research 15, nr 6 (17.05.2005): 809–19. http://dx.doi.org/10.1101/gr.3368805.

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13

Monterrubio, Rafael, Laura Baldoma, Nuria Obradors, Juan Aguilar i Josefa Badia. "A Common Regulator for the Operons Encoding the Enzymes Involved in d-Galactarate, d-Glucarate, and d-Glycerate Utilization in Escherichia coli". Journal of Bacteriology 182, nr 9 (1.05.2000): 2672–74. http://dx.doi.org/10.1128/jb.182.9.2672-2674.2000.

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ABSTRACT Genes for d-galactarate (gar) andd-glucarate (gud) metabolism inEscherichia coli are organized in three transcriptional units: garD, garPLRK, and gudPD. Two observations suggested a common regulator for the three operons. (i) Their expression was triggered by d-galactarate,d-glucarate, and d-glycerate. (ii) Metabolism of the three compounds was impaired by a single Tn5insertion mapped in the yaeG gene (proposed name,sdaR), outside the d-galactarate andd-glucarate systems. Expression of the sdaRgene is autogenously regulated.

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14

Qian, W., i J. Zhang. "Evolutionary dynamics of nematode operons: Easy come, slow go". Genome Research 18, nr 3 (6.02.2008): 412–21. http://dx.doi.org/10.1101/gr.7112608.

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Huang, P., E. D. Pleasance, J. S. Maydan, R. Hunt-Newbury, N. J. O'Neil, A. Mah, D. L. Baillie, M. A. Marra, D. G. Moerman i S. J. M. Jones. "Identification and analysis of internal promoters in Caenorhabditis elegans operons". Genome Research 17, nr 10 (4.09.2007): 1478–85. http://dx.doi.org/10.1101/gr.6824707.

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Hudson, Kaye D., Bernard M. Corfe, E. Helen Kemp, Ian M. Feavers, Peter J. Coote i Anne Moir. "Localization of GerAA and GerAC Germination Proteins in the Bacillus subtilis Spore". Journal of Bacteriology 183, nr 14 (15.07.2001): 4317–22. http://dx.doi.org/10.1128/jb.183.14.4317-4322.2001.

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ABSTRACT The GerAA, -AB, and -AC proteins of the Bacillus subtilis spore are required for the germination response tol-alanine as the sole germinant. They are likely to encode the components of the germination apparatus that respond directly to this germinant, mediating the spore's response; multiple homologues of the gerA genes are found in every spore former so far examined. The gerA operon is expressed in the forespore, and the level of expression of the operon appears to be low. The GerA proteins are predicted to be membrane associated. In an attempt to localize GerA proteins, spores of B. subtilis were broken and fractionated to give integument, membrane, and soluble fractions. Using antibodies that detect Ger proteins specifically, as confirmed by the analysis of strains lacking GerA and the related GerB proteins, the GerAA protein and the GerAC+GerBC protein homologues were localized to the membrane fraction of fragmented spores. The spore-specific penicillin-binding protein PBP5∗, a marker for the outer forespore membrane, was absent from this fraction. Extraction of spores to remove coat layers did not release the GerAC or AA protein from the spores. Both experimental approaches suggest that GerAA and GerAC proteins are located in the inner spore membrane, which forms a boundary around the cellular compartment of the spore. The results provide support for a model of germination in which, in order to initiate germination, germinant has to permeate the coat and cortex of the spore and bind to a germination receptor located in the inner membrane.

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Decker, Philip. "Wagner in Moscow, Glinka in Berlin: An Exchange of Operas during the Molotov-Ribbentrop Years". German Studies Review 45, nr 3 (październik 2022): 429–53. http://dx.doi.org/10.1353/gsr.2022.0046.

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18

Paidhungat, Madan, i Peter Setlow. "Role of Ger Proteins in Nutrient and Nonnutrient Triggering of Spore Germination in Bacillus subtilis". Journal of Bacteriology 182, nr 9 (1.05.2000): 2513–19. http://dx.doi.org/10.1128/jb.182.9.2513-2519.2000.

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ABSTRACT Dormant Bacillus subtilis spores germinate in the presence of particular nutrients called germinants. The spores are thought to recognize germinants through receptor proteins encoded by the gerA family of operons, which includesgerA, gerB, and gerK. We sought to substantiate this putative function of the GerA family proteins by characterizing spore germination in a mutant strain that contained deletions at all known gerA-like loci. As expected, the mutant spores germinated very poorly in a variety of rich media. In contrast, they germinated like wild-type spores in a chemical germinant, a 1-1 chelate of Ca2+ and dipicolinic acid (DPA). These observations showed that proteins encoded bygerA family members are required for nutrient-induced germination but not for chemical-triggered germination, supporting the hypothesis that the GerA family encodes receptors for nutrient germinants. Further characterization of Ca2+–DPA-induced germination showed that the effect of Ca2+–DPA on spore germination was saturated at 60 mM and had a Km of 30 mM. We also found that decoating spores abolished their ability to germinate in Ca2+–DPA but not in nutrient germinants, indicating that Ca2+–DPA and nutrient germinants probably act through parallel arms of the germination pathway.

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Lercher, M. J. "Coexpression of Neighboring Genes in Caenorhabditis Elegans Is Mostly Due to Operons and Duplicate Genes". Genome Research 13, nr 2 (1.02.2003): 238–43. http://dx.doi.org/10.1101/gr.553803.

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Wang, R. "Mass spectrometry of the M. smegmatis proteome: Protein expression levels correlate with function, operons, and codon bias". Genome Research 15, nr 8 (1.08.2005): 1118–26. http://dx.doi.org/10.1101/gr.3994105.

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Kelley, Ann E., i Christopher G. Lang. "Effects of GBR 12909, a selective dopamine uptake inhibitor, on motor activity and operant behavior in the rat". European Journal of Pharmacology 167, nr 3 (sierpień 1989): 385–95. http://dx.doi.org/10.1016/0014-2999(89)90447-0.

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Mudahi-Orenstein, Sigalit, Sharon Levisohn, Steven J. Geary i David Yogev. "Cytadherence-Deficient Mutants of Mycoplasma gallisepticum Generated by Transposon Mutagenesis". Infection and Immunity 71, nr 7 (lipiec 2003): 3812–20. http://dx.doi.org/10.1128/iai.71.7.3812-3820.2003.

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ABSTRACT Cytadherence-related molecules of Mycoplasma gallisepticum strain R-low were identified by Tn4001 transposon mutagenesis with the hemadsorption (HA) assay as an indicator for cytadherence. Three Gmr HA-negative (HA−) colonies displaying a stable HA− phenotype through several successive generations in which gentamicin selection was maintained were isolated from four independent transformation experiments and characterized. Southern blot analysis showed that the transposon was inserted as a single copy within the genome of each of the HA− mutants, suggesting that the transposon insertion was directly responsible for their inability to attach to erythrocytes. Sequence analysis of the transposon insertion sites revealed that in two mutants, the transposon was inserted at two distinct sites within the gapA structural gene. In the third mutant, the insertion was mapped within the crmA gene, which is located immediately downstream of the gapA gene as part of the same operon. In vitro attachment experiments with the MRC-5 human lung fibroblast cell line showed that the cytadherence capabilities of the HA− mutants were less than 25% those of original strain R. Experimental infection of chickens, the natural host of M. gallisepticum, with each of the three mutants demonstrated significantly impaired colonization and host responses. These data demonstrate conclusively the role of both GapA and CrmA proteins in the adherence of M. gallisepticum to host cells in model systems and in vivo colonization. Furthermore, these results underscore the relevance of in vitro cytadherence model systems for studying the pathogenesis of natural infections in chickens.

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Altan, Sümeyra, Bercim Berberoglu, Sinan Canan i Şenol Dane. "Effects of neurofeedback therapy in healthy young subjects". Clinical & Investigative Medicine 39, nr 6 (1.12.2016): 27. http://dx.doi.org/10.25011/cim.v39i6.27496.

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Purpose: Neurofeedback refers to a form of operant conditioning of electrical brain activity, in which desirable brain activity is rewarded and undesirable brain activity is inhibited. The research team aimed to examine the efficacy of neurofeedback therapy on electroencephalogram (EEG) for heart rate, electrocardiogram (ECG) and galvanic skin resistance (GSR) parameters in a healthy young male population. Methods: Forty healthy young male subjects aged between 18 to 30 years participated in this study. Neurofeedback application of one session was made with bipolar electrodes placed on T3 and T4 (temporal 3 and 4) regions and with reference electrode placed on PF1 (prefrontal 1). Electroencephalogram (EEG), electrocardiogram (ECG) and galvanic skin resistance (GSR) were assessed during Othmer neurofeedback application of one session to regulate slow wave activity for forty minutes thorough the session. Data assessed before neurofeedback application for 5 minutes and during neurofeedback application of 30 minutes and after neurofeedback application for 5 minutes throughout the session of 40 minutes. Means for each 5 minutes, that is to say, a total 8 data points for each subjects over 40 minutes, were assessed. Results: Galvanic skin resistance increased and heart rate decreased after neurofeedback therapy. Beta activity in EEG increased and alfa activity decreased after neurofeedback therapy. Conclusions: These results suggest that neurofeedback can be used to restore sympathovagal imbalances. Also, it may be accepted as a preventive therapy for psychological and neurological problems.

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Yilmaz, Recep, i Abdullah Hamarat. "Otomatik Kütle Yüklemeli Pistonlu Basınç Standardı ile Referans Basınç Uygulaması". Academic Perspective Procedia 1, nr 1 (9.11.2018): 603–11. http://dx.doi.org/10.33793/acperpro.01.01.113.

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Pistonlu basın&ccedil; standartları alanı y&uuml;ksek doğrulukta bilinen piston-silindir &uuml;nitesi &uuml;zerine k&uuml;tle setleri kullanılarak kuvvet etki ettirilmesi suretiyle referans basın&ccedil; değerinin elde edilmesi prensibine g&ouml;re &ccedil;alışmaktadır. Gerek hidrolik gerekse pn&ouml;matik pistonlu basın&ccedil; standartlarının kullanılmasında en &ouml;nemli zorluklardan biri her basın&ccedil; noktasında k&uuml;tle setlerinin yeniden y&uuml;klenmesi veya yeni k&uuml;tle kombinasyonunun oluşturulmasıdır. Basın&ccedil; değerlerinin manuel olarak oluşturulması zaman kaybının yanı sıra, operat&ouml;rden kaynaklanabilecek yanlış y&uuml;kleme gibi istenmeyen &ccedil;alışma koşullarına neden olabilmektedir. Bu &ccedil;alışmada otomatik k&uuml;tle y&uuml;klemeli pistonlu basın&ccedil; standardı (AMH-38 ile birlikte PG-7601 platformu) tanıtılmakta, bu sistem kullanılarak kalibrasyonun ger&ccedil;ekleştirme aşamaları anlatılmakta ve elde edilen sonu&ccedil;lar paylaşılmaktadır.

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Kintz, Erica, Christian Heiss, Ian Black, Nicholas Donohue, Naj Brown, Mark R. Davies, Parastoo Azadi, Stephen Baker, Paul M. Kaye i Marjan van der Woude. "Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition". Infection and Immunity 85, nr 4 (6.02.2017). http://dx.doi.org/10.1128/iai.01021-16.

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ABSTRACT Salmonella enterica serovar Typhi is a human-restricted Gram-negative bacterial pathogen responsible for causing an estimated 27 million cases of typhoid fever annually, leading to 217,000 deaths, and current vaccines do not offer full protection. The O-antigen side chain of the lipopolysaccharide is an immunodominant antigen, can define host-pathogen interactions, and is under consideration as a vaccine target for some Gram-negative species. The composition of the O-antigen can be modified by the activity of glycosyltransferase (gtr) operons acquired by horizontal gene transfer. Here we investigate the role of two gtr operons that we identified in the S. Typhi genome. Strains were engineered to express specific gtr operons. Full chemical analysis of the O-antigens of these strains identified gtr-dependent glucosylation and acetylation. The glucosylated form of the O-antigen mediated enhanced survival in human serum and decreased complement binding. A single nucleotide deviation from an epigenetic phase variation signature sequence rendered the expression of this glucosylating gtr operon uniform in the population. In contrast, the expression of the acetylating gtrC gene is controlled by epigenetic phase variation. Acetylation did not affect serum survival, but phase variation can be an immune evasion mechanism, and thus, this modification may contribute to persistence in a host. In murine immunization studies, both O-antigen modifications were generally immunodominant. Our results emphasize that natural O-antigen modifications should be taken into consideration when assessing responses to vaccines, especially O-antigen-based vaccines, and that the Salmonella gtr repertoire may confound the protective efficacy of broad-ranging Salmonella lipopolysaccharide conjugate vaccines.

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Aspholm, Marina, Kristina Borch-Pedersen, Kristin O’Sullivan, Siri Fjellheim, Inger-Helene Bjørnson Aardal, Per Einar Granum i Toril Lindbäck. "Importance of Individual Germination Receptor Subunits in the Cooperative Function between GerA and Ynd". Journal of Bacteriology 201, nr 21 (19.08.2019). http://dx.doi.org/10.1128/jb.00451-19.

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ABSTRACT Germination of Bacillus spores is triggered by the binding of specific nutrients to germinant receptors (GRs) located in the spore’s inner membrane. The GRs typically consist of A, B, and C subunits, encoded by tricistronic ger operons. The Bacillus licheniformis genome contains the gerA family operons gerA, ynd, and gerK. In contrast to the ABC(D) organization that characterizes gerA operons of many Bacillus species, B. licheniformis genomes contain a pentacistronic ynd operon comprising the yndD, yndE3, yndE2, yndF1, and yndE1 genes encoding A, B, B, C, and B GR subunits, respectively (subscripts indicate paralogs). Here we show that B. licheniformis spores can germinate in the absence of the Ynd and GerK GRs, although cooperation between all three GRs is required for optimal germination with amino acids. Spores carrying an incomplete set of Ynd B subunits demonstrated reduced germination efficiencies, while depletion of all three Ynd B subunits restored germination of the spore population to levels only slightly lower than those of wild-type spores at high germinant concentrations. This suggests that the presence of an incomplete set of Ynd B subunits exhibits a dominant negative effect on germination and that the A and C subunits of the Ynd GR are sufficient for the cooperative functionality between Ynd and GerA. In contrast to the B subunits of Ynd, the B subunit of GerA was essential for amino acid-induced germination. This study provides novel insights into the role of individual GR subunits in the cooperative interaction between GRs in triggering spore germination. IMPORTANCE Spore-forming bacteria are problematic for the food industry, as spores can survive decontamination procedures and subsequently revive in food products, with the risk of food spoilage and foodborne disease. The Ynd and GerA germination receptors (GRs) cooperate in triggering efficient germination of Bacillus licheniformis spores when nutrients are present in the surrounding environment. This study shows that the single B subunit of GerA is essential for the cooperative function between Ynd and GerA, while the three B subunits of the Ynd GR are dispensable. The ability of GRs lacking individual subunits to stimulate germination together with other GRs could explain why ger operons lacking GR subunit genes are maintained in genomes of spore-forming species.

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Guerreiro, Duarte N., Aoife Boyd i Conor P. O'Byrne. "The stressosome is required to transduce low pH signals leading to increased transcription of the amino acid-based acid tolerance mechanisms in Listeria monocytogenes". Access Microbiology 4, nr 9 (14.09.2022). http://dx.doi.org/10.1099/acmi.0.000455.

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Increasing proton concentration in the environment represents a potentially lethal stress for single-celled microorganisms. To survive in an acidifying environment, the foodborne pathogen Listeria monocytogenes quickly activates the alternative sigma factor B (σB), resulting in upregulation of the general stress response (GSR) regulon. Activation of σB is regulated by the stressosome, a multi-protein sensory complex involved in stress detection and signal transduction. In this study, we used L. monocytogenes strains harbouring two stressosome mutants to investigate the role of this complex in triggering expression of known amino acid-based resistance mechanisms in response to low pH. We found that expression of glutamate decarboxylase (gadD3) and arginine and agmatine deiminases (arcA and aguA1, respectively) were upregulated upon acid shock (pH 5 for 15 min) in a stressosome-dependent manner. In contrast, transcription of the arg operons (argGH and argCJBDF), which encode enzymes for the l-arginine biosynthesis pathway, were upregulated upon acid shock in a stressosome-independent manner. Finally, we found that transcription of argR, which encodes a transcriptional regulator of the arc and arg operons, was largely unaffected by acidic shock. Thus, our findings suggest that the stressosome plays a role in activating amino acid-based pH homeostatic mechanisms in L. monocytogenes . Additionally, we show that genes encoding the l-arginine biosynthesis pathway are highly upregulated under acidic conditions, suggesting that intracellular arginine can help withstand environmental acidification in this pathogen.

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"Ernest James William Barrington, 17 February 1909 - 15 December 1985". Biographical Memoirs of Fellows of the Royal Society 35 (marzec 1990): 37–54. http://dx.doi.org/10.1098/rsbm.1990.0002.

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Ernest James William Barrington was born on 17 February 1909 in Putney, the only son of William Benedict and Harriet Barrington. Little is known of his father and mother except that his father was a church warden and clerk at a local brewery, Messers Mann Crossman & Company. Ernest Barrington attended Christ’s Hospital School at Horsham where his interests and ability in music soon became evident. He studied with a Mrs Wright and is remembered by a contemporary school fellow, Sir William Glock, the noted musicologist and one-time Music Controller of the BBC, as a gifted pianist with an enviable fluency. This ability was demonstrated by the fact that he became an ARCO in 1926 at the age of seventeen and an LRAM the year later. In this year, 1927, he went up to Oriel College, Oxford, on an organ scholarship. Music and zoology began to vie for his interest. He took four years over his degree, gaining a first class honours B.A. in zoology in 1931. He obtained a grant from the Christopher Welch Trust during his four years at Oxford which enabled him not only to read zoology but also music. He completed the paper work for his Mus.B. But did not complete the degree. While at Oxford Ernest Barrington came under the influence of two great zoologists, T.S. Goodrich the Linacre Professor of Zoology and G.R. de Beer, fellow of Merton College and lecturer in comparative and experimental embryology. Gavin de Beer was Barrington’s tutor and was also knowledgeable about music and enjoyed playing the piano. For one pupil, at least, tutorial periods occasionally ended in a session of ebullient duet playing. As a student opera was not neglected and together with his undergraduate, and lifelong, friend Tom Hughes, Barrington went often to London, particularly to Wagner operas.

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