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:Co-immunoprecipitation with endogenous Hfq3xFlag in exponential, stationary, non-induced and virulence induced conditions, followed by RNA-sequencing, revealed 1697 mRNAs and 208 ncRNAs associated with Hfq. We identified 56 new ncRNAs and validated 3 Hfq-dependent trans sRNAs on by Northern blot analysis. Interestingly, 55% of the ncRNAs were encoded antisense to a protein coding sequence. Abundance of 4 asRNAs and their corresponding target mRNAs was altered upon hfq, indicating a substantial influence of Hfq on asRNA-target interactions.
Project description:Co-immunoprecipitation with endogenous Hfq3xFlag in exponential, stationary, non-induced and virulence induced conditions, followed by RNA-sequencing, revealed 1697 mRNAs and 208 ncRNAs associated with Hfq. We identified 56 new ncRNAs and validated 3 Hfq-dependent trans sRNAs on by Northern blot analysis. Interestingly, 55% of the ncRNAs were encoded antisense to a protein coding sequence. Abundance of 4 asRNAs and their corresponding target mRNAs was altered upon hfq, indicating a substantial influence of Hfq on asRNA-target interactions. 8 cDNA libraries were sequenced. A. tumefaciens hfq3xFlag and hfqWT (control) strains were grown to stationary and exponential growth phase and under non-induced and virulence induced conditions.
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: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:The RNA-chaperone Hfq is a global post-transcriptional regulator in Bacteria, important especially for the fine-tuning of the gene expression when the environmental conditions change. We looked into sRNAome during the growth of Pseudomonas putida KT2440 and compared it to a strain without Hfq protein. Numerous sRNAs were upregulated at a specific point during the growth and many were affected in the Hfq absence. Further we identified Hfq-binding RNA transcripts with co-immunoprecipitation and experimentally validated 17 sRNAs. Many novel Hfq-binding sRNAs were identified and are directly or indirectly regulated by Hfq. In addition 1870 mRNAs were found to bind to Hfq during the growth. Together, 202 antisense and 355 intergenic sRNAs have been detected in this study, several of them being 3’UTR- or 5’UTR-derived, and IS-related.
Project description:Small RNAs are important for post-transcriptional regulation of gene expression, affecting stability and activity of their target mRNAs. The bacterial Sm-like protein Hfq is required to promote pairing between both RNAs when their sequence complementarity is limited. To provide a first global view on the post-transcriptional landscape of the α-proteobacterium Caulobacter crescentus, we have identified the Hfq-binding RNAs employing High-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP). A total of 261 RNAs, including 3 unannotated RNAs, were successfully identified and classified according to putative function. Moreover, possible interactions between the identified sRNAs with mRNA targets were postulated through computational target predictions.
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.