Project description:The alpha-proteobacterium Caulobacter crescentus thrives in oligotrophic environments and is able to optimally exploit minimal resources by entertaining an intricate network of gene expression control mechanisms. Numerous transcriptional activators and repressors have been reported to contribute to these processes, but only few studies have focused on regulation at the post-transcriptional level in C. crescentus. Small RNAs (sRNAs) are a prominent class of regulators of bacterial gene expression, and most sRNAs characterized today engage in direct base-pairing interactions to modulate translation and/or stability of target mRNAs. In many cases, the ubiquitous RNA chaperone, Hfq, contributes to the establishment of RNA-RNA interactions. Although the deletion of the hfq gene is associated with a severe loss of fitness in C. crescentus, the RNA ligands of the chaperone have remained largely unexplored. Here we report on the identification of coding and non-coding transcripts associated with Hfq in C. crescentus, and demonstrate Hfq-dependent post-transcriptional regulation in this organism. We show that the conserved, Hfq-bound sRNA RusT is transcriptionally controlled by the conserved NtrYX two-component system and induced in response to iron starvation. By combining RusT pulse expression with whole-genome transcriptome analysis we determine 16 candidate target transcripts, more than half of which encode outer membrane transporters. We hence suggest RusT to support remodeling of the C. crescentus cell surface when iron supplies are limiting.
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: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 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:The alphaproteobacterium Caulobacter crescentus thrives in oligotrophic environments and is able to optimally exploit minimal resources by entertaining an intricate network of gene expression control mechanisms. Numerous transcriptional activators and repressors have been reported to contribute to these processes, but only few studies have focused on regulation at the post-transcriptional level in C. crescentus. Small RNAs (sRNAs) are a prominent class of regulators of bacterial gene expression, and most sRNAs characterized today engage in direct base-pairing interactions to modulate the translation and/or stability of target mRNAs. In many cases, the ubiquitous RNA chaperone, Hfq, contributes to the establishment of RNA-RNA interactions. Although the deletion of the hfq gene is associated with a severe loss of fitness in C. crescentus, the RNA ligands of the chaperone have remained largely unexplored. Here we report on the identification of coding and non-coding transcripts associated with Hfq in C. crescentus and demonstrate Hfq-dependent post-transcriptional regulation in this organism. We show that the Hfq-bound sRNA RusT is transcriptionally controlled by the NtrYX two-component system and induced in response to iron starvation. By combining RusT pulse expression with whole-genome transcriptome analysis, we determine 16 candidate target transcripts that are deregulated, many of which encode outer membrane transporters. We hence suggest RusT to support remodeling of the C. crescentus cell surface when iron supplies are limited.IMPORTANCEThe conserved RNA-binding protein Hfq contributes significantly to the adaptation of bacteria to different environmental conditions. Hfq not only stabilizes associated sRNAs but also promotes inter-molecular base-pairing interactions with target transcripts. Hfq plays a pivotal role for growth and survival, controlling central metabolism and cell wall synthesis in the oligotroph Caulobacter crescentus. However, direct evidence for Hfq-dependent post-transcriptional regulation and potential oligotrophy in C. crescentus has been lacking. Here, we identified sRNAs and mRNAs associated with Hfq in vivo, and demonstrated the requirement of Hfq for sRNA-mediated regulation, particularly of outer membrane transporters in C. crescentus.