Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
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: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 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 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 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.