The small proteome of the nitrogen-fixing plant symbiont Sinorhizobium meliloti
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ABSTRACT:
ORGANISM(S): Sinorhizobium meliloti 2011
PROVIDER: GSE206492 | GEO | 2023/02/14
REPOSITORIES: GEO
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Project description:The Alphaproteobacterium Sinorhizobium meliloti lives in soil and is capable of fixing molecular nitrogen in symbiosis with legume plants. In this work, the small proteome of S. meliloti strain 2011 was studied to uncover translation of both annotated and novel small open reading frame (sORF)-encoded proteins (SEPs).
2023-03-13 | PXD034931 | Pride
Project description:Differences in genome size and gene content are among the most important signatures of microbial adaptation and genome evolution. Here, we investigated the patterns of genome variation among strains of the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti. Using the sequenced strain Rm1021 as a reference, the genome size and gene content variations were analyzed among ten diverse natural strains, through pulse field gel electrophoresis (PFGE) and whole-genome microarray hybridizations. Our PFGE analysis showed a genome size range of 6.45-7.01Mbp, with the greatest variation arising from the pSymA replicon, followed by that of pSymB. No observable size difference was evident among the chromosomes. Consistent with this pattern of size differences, 41.2% of ORFs on pSymA were variably absent/present, followed by 12.7% on pSymB, and 3.7% on the chromosome. However, the percentages of ORFs that were variably duplicated were more evenly distributed among the three replicons, 11.0%, 16.5% and 15.3% respectively for ORFs on pSymA, pSymB and the chromosome. Among the 10 strains, the percentages of absent ORFs ranged from 1.51% to 6.35% and those of duplicated ORFs ranged from 0.27% to 8.56%. Our analyses showed that host plants, geographic origins, multilocus enzyme electrophoretic types, and replicon sizes had little influence on the distribution patterns of absent or duplicated ORFs. The proportions of ORFs that were either variably absent/present or variably duplicated differed greatly among the functional categories, for each of the three replicons as well as for the whole genome. Interestingly, we observed positive correlations among the three replicons in their numbers of absent ORFs as well as the numbers of duplicated ORFs, consistent with coordinated gene gains/losses in this important bacterium in nature. microarray:Sm6kOligo
2009-05-01 | GSE15889 | GEO
Project description:Differences in genome size and gene content are among the most important signatures of microbial adaptation and genome evolution. Here, we investigated the patterns of genome variation among strains of the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti. Using the sequenced strain Rm1021 as a reference, the genome size and gene content variations were analyzed among ten diverse natural strains, through pulse field gel electrophoresis (PFGE) and whole-genome microarray hybridizations. Our PFGE analysis showed a genome size range of 6.45-7.01Mbp, with the greatest variation arising from the pSymA replicon, followed by that of pSymB. No observable size difference was evident among the chromosomes. Consistent with this pattern of size differences, 41.2% of ORFs on pSymA were variably absent/present, followed by 12.7% on pSymB, and 3.7% on the chromosome. However, the percentages of ORFs that were variably duplicated were more evenly distributed among the three replicons, 11.0%, 16.5% and 15.3% respectively for ORFs on pSymA, pSymB and the chromosome. Among the 10 strains, the percentages of absent ORFs ranged from 1.51% to 6.35% and those of duplicated ORFs ranged from 0.27% to 8.56%. Our analyses showed that host plants, geographic origins, multilocus enzyme electrophoretic types, and replicon sizes had little influence on the distribution patterns of absent or duplicated ORFs. The proportions of ORFs that were either variably absent/present or variably duplicated differed greatly among the functional categories, for each of the three replicons as well as for the whole genome. Interestingly, we observed positive correlations among the three replicons in their numbers of absent ORFs as well as the numbers of duplicated ORFs, consistent with coordinated gene gains/losses in this important bacterium in nature. microarray:Sm6kOligo A total of 12 strains were included for the microarray analyses in this study. The 12 strains included two reference strains and ten other natural strains. Reference strain Rm1021 was the strain with a completely sequenced genome, from which the whole genome microarray was based on (Krol et al. 2004). The second reference strain RmF909 was derived from strain Rm1021 but with a deletion of 575 ORFs located on the megaplasmid pSymB (genomic location 106724-735431, Charles et al. 1991). The two reference strains were used for positive and negative controls in our microarray hybridization experiments and for establishing threshold values for determining whether an ORF is present or absent among natural strains.
2010-05-19 | E-GEOD-15889 | biostudies-arrayexpress
Project description:In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle regulated transcription plays an important role in control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled the first global analysis of S. meliloti cell cycle regulated gene expression. The objective of the microarray-based cell cycle gene expression analysis was to determine which genes were transcriptionally regulated as a funciton of a cell cycle in order to understand the contribution of transcriptional regulation to the timing of cell cycle events. The microarray analysis identified 462 genes with cell cycle regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle regulated genes were also transcriptionally cell cycle regulated in C. crescentus. Furthermore, CtrA and DnaA binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria. Gene expression levels were quantified in synchronously growing S. meliloti cultures across 8 time points and compared to gene expression levels in unsynchronized culture via a two-color custom agilent array
2014-01-22 | GSE54208 | GEO
Project description:Open reading frame (ORF) boundaries in bacterial genomes have largely been drawn by gene prediction algorithms. However, these algorithms often fail to predict ORFs with non-canonical features, including those that are short, overlapping, or lack 5’ UTRs. Recent developments in genome-scale mapping of translation have facilitated the empirical identification of open reading frames (ORFs). Here, we use ribosome profiling approaches to map initiating and elongating ribosomes in Mycobacterium tuberculosis. Thus, we identify over 1,000 novel ORFs, revealing that much of the M. tuberculosis genome encodes proteins in overlapping reading frames, and/or on both strands. Most of the novel ORFs are short (sORFs), impeding their identification by traditional methods. The strong codon bias that characterizes annotated mycobacterial ORFs is not evident in the aggregate novel sORFs, and hence most are unlikely to encode functional proteins. Thus, our data suggest that bacterial transcriptomes are subject to pervasive translation that occurs as a result of the relatively low specificity requirements of initiating ribosomes. We speculate that the inefficiency of expressing spurious sORFs may be offset by positive contributions to M. tuberculosis biology through cis and trans regulatory activities of a small subset.
2019-06-20 | E-MTAB-8039 | biostudies-arrayexpress
Project description:Sinorhizobium meliloti, a facultative microsymbiont of alfalfa, should fine-tune its cellular processes to live saprophytically in soils characterized with limited nutrients and diverse stresses. In this study, TiO2 enrichment and LC-MS/MS were used to uncover the site-specific Ser/Thr/Tyr phosphoproteome of S. meliloti in minimum medium at stationary phase. There are a total of 96 unique phosphorylated sites, with a Ser/Thr/Tyr distribution of 65:32:5, in 78 proteins. Phosphoproteins identified in S. meliloti showed a wide distribution pattern regarding to functional categories, such as replication, transcription, translation, posttranslational modification, transport and metabolism of amino acids, carbohydrate, inorganic ion, succinoglycan etc. Ser/Thr/Tyr phosphosites identified within the conserved motif in proteins of key cellular function indicate a crucial role of phosphorylation in modulating cellular physiology. Moreover, phosphorylation events potentially involved in rhizobial adaptation to diverse stresses were also discussed, such as those identified in SMa0114 and PhaP2 (polyhydroxybutyrate synthesis), ActR (pH stress and microaerobic adaption), SupA (potassium stress), chaperonin GroEL2 (viability and potentially symbiosis), and ExoP (succinoglycan synthesis and secretion). These Ser/Thr/Tyr phosphosites identified herein would be helpful for our further investigation and understanding of the role of phosphorylation in rhizobial physiology.
2015-10-05 | PXD002064 | Pride
Project description:In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle regulated transcription plays an important role in control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled the first global analysis of S. meliloti cell cycle regulated gene expression. The objective of the microarray-based cell cycle gene expression analysis was to determine which genes were transcriptionally regulated as a funciton of a cell cycle in order to understand the contribution of transcriptional regulation to the timing of cell cycle events. The microarray analysis identified 462 genes with cell cycle regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle regulated genes were also transcriptionally cell cycle regulated in C. crescentus. Furthermore, CtrA and DnaA binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria. Gene expression levels were quantified in synchronously growing S. meliloti cultures across 8 time points and compared to gene expression levels in unsynchronized culture via a two-color custom agilent array A two-color array format was used with time point from synchronous culture being competed with a sample from unsynchronized culture (control same for all arrays) to determine the cell cycle-phase specific induction or repression of genes relative to batch culture which contains cells in all phases of the cell cycle. For each of the 8 cell cycle time points, four biological replicates were used resulting in 4 arrays per time point and a total of 32 arrays. The arrays also contained duplicates of each probe resulting in two technical replicates per biological replicate per time point.
2014-01-22 | E-GEOD-54208 | biostudies-arrayexpress
Project description:Sinorhizobium meliloti can live as a soil saprophyte, and can engage in a nitrogen fixing symbiosis with plant roots. To succeed in such diverse environments, the bacteria must continually adjust gene expression. Transcriptional plasticity in eubacteria is often mediated by alternative sigma factors interacting with core RNA polymerase. The S. meliloti genome encodes 14 of these alternative sigmas, including two putative RpoH (heat shock) sigmas. We used custom Affymetrix Symbiosis Chips to characterize the global transcriptional response of S. meliloti rpoH1, rpoH2 and rpoH1 rpoH2 mutants during heat shock and stationary phase growth. Under these conditions, expression of over 300 genes is dependent on rpoH1 and rpoH2.
2012-10-02 | GSE36186 | GEO
Project description:Sinorhizobium meliloti lives as a soil saprophyte, and engages in a nitrogen fixing symbiosis with plant roots. To succeed in such diverse environments, the bacteria must continually adjust gene expression. Transcriptional plasticity in eubacteria is often mediated by alternative sigma factors interacting with core RNA polymerase. The S. meliloti genome encodes 14 of these alternative sigmas, including 11 extracytoplasmic function (ECF) sigmas. We used custom Affymetrix Symbiosis Chips to characterize the global transcriptional response of S. meliloti overexpressing the ECF sigma factor, RpoE2. Our work identifies over 200 genes whose expression is dependent on RpoE2.
2013-07-22 | GSE40391 | GEO
Project description:The delineation of genes in bacteria has remained an important challenge because prokaryotic genomes are often tightly packed frequently resulting in overlapping genes. We hereby present a de novo approach called REPARATION (RibosomeE Profiling Assisted (Re-)AnnotaTION) to delineate translated open reading frames (ORFs) in bacteria independent of (available) genome annotation. By deep sequencing of ribosome protected mRNA fragments (RPF) to map translating ribosomes across the entire genome, REPARATION takes advantage of the recently developed ribosome profiling (Ribo-seq) technique. REPARATION starts by traversing the entire genome to generate all possible ORFs and then collects their corresponding RPF signal information. Based on a growth curve model to estimate minimum ORF read density and Ribo-seq RPF coverage, thresholds indicative of translation is estimated. Finally, our algorithm applies a random forest model to build a classifier to classify putative protein coding ORFs. We evaluated the performance of REPARATION on 3 annotated bacterial species using in-house generated Ribo-seq data and matching N-terminal and shotgun proteomics data next to publically available Ribo-seq data. In all cases, about 80% of the ORFs predicted by REPARATION were previously annotated as protein coding. While 13-20% were variants of previously annotated ORFs and about 3-4% point to novel translated ORFs within intergenic or other regions previously annotated as non-coding. Without stringent length restrictions REPARATION was able to identify several small ORFs (sORFs). Multiple supportive evidence from matching MS data and sequence conservation analysis was obtained to validate predicted ORFs.
2017-01-30 | GSE91066 | GEO