Project description:Two-component systems (TCS) are often used by bacteria to rapidly assess and respond to environmental changes. ChvG/ChvI (ChvGI) is a TCS conserved in γ-proteobacteria and is known for regulating expression of genes related to exopolysaccharide production, virulence and growth. The sensor kinase ChvG autophosphorylates upon yet unknown signals and phosphorylates the response regulator ChvI to activate transcription. Recent studies in Caulobacter crescentus showed that chv mutants are sensitive to vancomycin treatment and fail to grow in synthetic minimal media. In this work, we identified the osmotic imbalance as the main cause of growth impairment in synthetic minimal media. We also determined the ChvI regulon and confirmed that ChvI regulates cell envelope architecture at different levels by controlling outer membrane, peptidoglycan assembly/recycling and inner membrane proteins. Furthermore, we identified genes with osmoregulatory properties and confirmed that osmotic upshift is a signal triggering ChvG-dependent phosphorylation of ChvI. In addition, we challenged chv mutants with other cell envelope related stress and found that targeting with antibiotics the transpeptidation of peptidoglycan during cell elongation impairs growth of the mutant. Moreover, these antibiotics activate expression of the chvIG-hprK operon in ChvI-dependent and independent ways. ChvI phosphorylation is also shown to be activated upon antibiotic treatment with vancomycin. Finally, we observed that the sensor kinase ChvG fused to a fluorescent protein relocates from a patchy-spotty distribution to distinctive foci after transition from complex to synthetic minimal media. Interestingly, this pattern of (re)location has been described for proteins involved in cell growth control and peptidoglycan synthesis upon osmotic shock. Overall, our data support that the ChvGI TCS is mainly used to monitor and respond to osmotic imbalances and damages in the peptidoglycan layer.
Project description:Two-component systems (TCS) are often used by bacteria to rapidly assess and respond to environmental changes. ChvG/ChvI (ChvGI) is a TCS conserved in γ-proteobacteria and is known for regulating expression of genes related to exopolysaccharide production, virulence and growth. The sensor kinase ChvG autophosphorylates upon yet unknown signals and phosphorylates the response regulator ChvI to activate transcription. Recent studies in Caulobacter crescentus showed that chv mutants are sensitive to vancomycin treatment and fail to grow in synthetic minimal media. In this work, we identified the osmotic imbalance as the main cause of growth impairment in synthetic minimal media. We also determined the ChvI regulon and confirmed that ChvI regulates cell envelope architecture at different levels by controlling outer membrane, peptidoglycan assembly/recycling and inner membrane proteins. Furthermore, we identified genes with osmoregulatory properties and confirmed that osmotic upshift is a signal triggering ChvG-dependent phosphorylation of ChvI. In addition, we challenged chv mutants with other cell envelope related stress and found that targeting with antibiotics the transpeptidation of peptidoglycan during cell elongation impairs growth of the mutant. Moreover, these antibiotics activate expression of the chvIG-hprK operon in ChvI-dependent and independent ways. ChvI phosphorylation is also shown to be activated upon antibiotic treatment with vancomycin. Finally, we observed that the sensor kinase ChvG fused to a fluorescent protein relocates from a patchy-spotty distribution to distinctive foci after transition from complex to synthetic minimal media. Interestingly, this pattern of (re)location has been described for proteins involved in cell growth control and peptidoglycan synthesis upon osmotic shock. Overall, our data support that the ChvGI TCS is mainly used to monitor and respond to osmotic imbalances and damages in the peptidoglycan layer.
Project description:This SuperSeries is composed of the following subset Series: GSE25996: Expression data from Caulobacter crescentus starved for carbon GSE25997: Expression data from Caulobacter crescentus (syn. C. vibrioides) swarmer and stalked cells starved for carbon GSE25998: Expression data from WT, DSigT and DSigU Caulobacter crescentus (syn. C. vibrioides) starved for carbon Refer to individual Series
Project description:Investigation of whole genome gene expression level changes in a Caulobacter crescentus NA1000 delta-CCNA_00382 (ccrM) mutant, compared to the wild-type strain. The mutations engineered into this strain render it incapable of methylating its genome on the adenine at GANTC motifs. References for strains : WT: Marks, M.E., Castro-Rojas, C.M., Teiling, C., Du, L., Kapatral, V., Walunas, T.L. and Crosson, S. (2010) The genetic basis of laboratory adaptation in Caulobacter crescentus. J Bacteriol, 192, 3678-3688; Collier, J. and Shapiro, L. (2009) Feedback control of DnaA-mediated replication initiation by replisome-associated HdaA protein in Caulobacter. J Bacteriol, 191, 5706-5716. DccrM: Gonzalez, D. and Collier, J. (2013) DNA methylation by CcrM activates the transcription of two genes required for the division of Caulobacter crescentus. Mol Microbiol, 88, 203-218. A six chip study using total RNA recovered from three separate wild-type cultures of Caulobacter crescentus NA1000 and three separate cultures of a triple mutant strain, Caulobacter crescentus NA1000 delta-CCNA_00382 (ccrM), in which the ccrM gene coding for a DNA methyltransferase methylating the adenine in GANTC motifs is truncated and its product inactive. Each chip measures the expression level of 3933 genes from Caulobacter crescentus NA1000 with 3 probes per gene and with three-fold technical redundancy.
Project description:Investigation of whole genome gene expression level changes in a Caulonacter crescentus NA1000 Plac::CCNA_00382 (ccrM) mutant, compared to the wild-type strain. The mutations engineered into this strain cause the CcrM DNA methyltransferase to be overexpressed and the chromosome to be constitutively methylated at the adenine at GANTC motifs. References of strains: CcrMOE: Collier, J. and Shapiro, L. (2009) Feedback control of DnaA-mediated replication initiation by replisome-associated HdaA protein in Caulobacter. J Bacteriol, 191, 5706-5716. WT: Marks, M.E., Castro-Rojas, C.M., Teiling, C., Du, L., Kapatral, V., Walunas, T.L. and Crosson, S. (2010) The genetic basis of laboratory adaptation in Caulobacter crescentus. J Bacteriol, 192, 3678-3688; Collier, J. and Shapiro, L. (2009) Feedback control of DnaA-mediated replication initiation by replisome-associated HdaA protein in Caulobacter. J Bacteriol, 191, 5706-5716. A six chip study using total RNA recovered from three separate wild-type cultures of Caulonacter crescentus NA1000 and three separate cultures of a triple mutant strain, Caulonacter crescentus NA1000 Plac::CCNA_00382 (ccrM), in which the ccrM gene coding for a DNA methyltransferase methylating the adenine in GANTC motifs is truncated and its product inactive. Each chip measures the expression level of 3933 genes from Caulobacter crescentus NA1000 with 3 probes per gene and with three-fold technical redundancy.
Project description:Investigation of whole genome gene expression level changes in a Caulobacter crescentus NA1000 dcdnL mutant, compared to the wild-type strain. In bacteria, transcription of housekeeping genes required for metabolic homeostasis and cell proliferation is guided by the sigma factor σ70. The conserved CarD-like transcriptional regulator, CdnL, associates with promoter regions where σ70 localizes and stabilizes the open promoter complex. Caulobacter crescentus cells lacking CdnL have severe morphological and growth defects. Our microarray experiment demonstrates how cdnL deletion affects the transcriptome of Caulobacter crescentus.
Project description:Caulobacter crescentus is an alphaproteobacterium that divides assymetrically. Each cell cycle results in the production of a motile flagellated cell and a sessile cell called the swamer cell and the stalked cell, respectively. The flagellar filament is composed of thousands polymerized flagellins. We showed that glycosylation of flagellins is required for the assembly of the flagellum. This glycosylation is performed by soluble FlmG glycosyltransferases that transfer nonulosonic acids (pseudaminic acid or legionaminic acid) directly to the flagellins. Such glycosylation system is also present in a close relative of Caulobacter crescentus, Brevundimonas subvibrioides. The project is to identify the site of glycosylation and the potential sugar added on this site.
Project description:Investigation of whole genome gene expression level changes in a Caulobacter crescentus NA1000 delta-CCNA_00382 (ccrM) mutant, compared to the wild-type strain. The mutations engineered into this strain render it incapable of methylating its genome on the adenine at GANTC motifs. References for strains : WT: Marks, M.E., Castro-Rojas, C.M., Teiling, C., Du, L., Kapatral, V., Walunas, T.L. and Crosson, S. (2010) The genetic basis of laboratory adaptation in Caulobacter crescentus. J Bacteriol, 192, 3678-3688; Collier, J. and Shapiro, L. (2009) Feedback control of DnaA-mediated replication initiation by replisome-associated HdaA protein in Caulobacter. J Bacteriol, 191, 5706-5716. DccrM: Gonzalez, D. and Collier, J. (2013) DNA methylation by CcrM activates the transcription of two genes required for the division of Caulobacter crescentus. Mol Microbiol, 88, 203-218.