A portal for rhizobial genomes: RhizoGATE integrates a Sinorhizobium meliloti genome annotation update with postgenome data.

Genetics and Systems Biology, Faculty of Biology, University of Freiburg, Freiburg, Germany.
Journal of Biotechnology (Impact Factor: 3.18). 01/2009; 140(1-2):45-50. DOI: 10.1016/j.jbiotec.2008.11.006
Source: PubMed

ABSTRACT Sinorhizobium meliloti is a symbiotic soil bacterium of the alphaproteobacterial subdivision. Like other rhizobia, S. meliloti induces nitrogen-fixing root nodules on leguminous plants. This is an ecologically and economically important interaction, because plants engaged in symbiosis with rhizobia can grow without exogenous nitrogen fertilizers. The S. meliloti-Medicago truncatula (barrel medic) association is an important symbiosis model. The S. meliloti genome was published in 2001, and the M. truncatula genome currently is being sequenced. Many new resources and data have been made available since the original S. meliloti genome annotation and an update was needed. In June 2008, we submitted our annotation update to the EMBL and NCBI databases. Here we describe this new annotation and a new web-based portal RhizoGATE. About 1000 annotation updates were made; these included assigning functions to 313 putative proteins, assigning EC numbers to 431 proteins, and identifying 86 new putative genes. RhizoGATE incorporates the new annotion with the S. meliloti GenDB project, a platform that allows annotation updates in real time. Locations of transposon insertions, plasmid integrations, and array probe sequences are available in the GenDB project. RhizoGATE employs the EMMA platform for management and analysis of transcriptome data and the IGetDB data warehouse to integrate a variety of heterogeneous external data sources.

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    ABSTRACT: Background Genetic models have been developed in divergent branches of the class Alphaproteobacteria to help answer a wide spectrum of questions regarding bacterial physiology. For example, Sinorhizobium meliloti serves as a useful representative for investigating rhizobia-plant symbiosis and nitrogen fixation, Caulobacter crescentus for studying cell cycle regulation and organelle biogenesis, and Zymomonas mobilis for assessing the potentials of metabolic engineering and biofuel production. A tightly regulated promoter that enables titratable expression of a cloned gene in these different models is highly desirable, as it can facilitate observation of phenotypes that would otherwise be obfuscated by leaky expression.ResultsWe compared the functionality of four promoter regions in S. meliloti (P araA , P tauA , P rhaR , and P melA ) by constructing strains carrying fusions to the uidA reporter in their genomes and measuring beta-glucuronidase activities when they were induced by arabinose, taurine, rhamnose, or melibiose. P tauA was chosen for further study because it, and, to a lesser extent, P melA , exhibited characteristics suitable for efficient modulation of gene expression. The levels of expression from P tauA depended on the concentrations of taurine, in both complex and defined media, in S. meliloti as well as C. crescentus and Z. mobilis. Moreover, our analysis indicated that TauR, TauC, and TauY are each necessary for taurine catabolism and substantiated their designated roles as a transcriptional activator, the permease component of an ABC transporter, and a major subunit of the taurine dehydrogenase, respectively. Finally, we demonstrated that P tauA can be used to deplete essential cellular factors in S. meliloti, such as the PleC histidine kinase and TatB, a component of the twin-arginine transport machinery.Conclusions The P tauA promoter of S. meliloti can control gene expression with a relatively inexpensive and permeable inducer, taurine, in diverse alpha-proteobacteria. Regulated expression of the same gene in different hosts can be achieved by placing both tauR and P tauA on appropriate vectors, thus facilitating inspection of conservation of gene function across species.
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    ABSTRACT: Denitrification is defined as the dissimilatory reduction of nitrate or nitrite to nitric oxide (NO), nitrous oxide (N2O), or dinitrogen gas (N2). N2O is a powerful atmospheric greenhouse gas and cause of ozone layer depletion. Legume crops might contribute to N2O production by providing nitrogen-rich residues for decomposition or by associating with rhizobia that are able to denitrify under free-living and symbiotic conditions. However, there are limited direct empirical data concerning N2O production by endosymbiotic bacteria associated with legume crops. Analysis of the Ensifer meliloti 1021 genome sequence revealed the presence of the napEFDABC, nirK, norECBQD and nosRZDFYLX denitrification genes. It was recently reported that this bacterium is able to grow using nitrate respiration when cells are incubated with an initial O2 concentration of 2%; however, these cells were unable to use nitrate respiration when initially incubated anoxically. The involvement of the nap, nirK, nor and nos genes in E. meliloti denitrification has not been reported.
    BMC Microbiology 06/2014; 14(1):142. · 2.98 Impact Factor
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    ABSTRACT: Post-transcriptional regulation by trans-encoded sRNAs, for example via base-pairing with target mRNAs, is a common feature in bacteria and influences various cell processes, e.g., response to stress factors. Several studies based on computational and RNA-seq approaches identified approximately 180 trans-encoded sRNAs in Sinorhizobium meliloti. The initial point of this report is a set of 52 trans-encoded sRNAs derived from the former studies. Sequence homology combined with structural conservation analyses were applied to elucidate the occurrence and distribution of conserved trans-encoded sRNAs in the order of Rhizobiales. This approach resulted in 39 RNA family models (RFMs) which showed various taxonomic distribution patterns. Whereas the majority of RFMs was restricted to Sinorhizobium species or the Rhizobiaceae, members of a few RFMs were more widely distributed in the Rhizobiales. Access to this data is provided via the RhizoGATE portal [1,2].
    Genes. 01/2011; 2(4):925-56.

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