title: The transcriptional regulator pool of the marine bacterium Rhodopirellula baltica SH 1T as revealed by whole genome comparisons.
abstract: Rhodopirellula baltica (strain SH 1T) is a free-living marine representative of the phylogenetically independent and environmentally relevant phylum Planctomycetes. Little is known about the regulatory strategies of free-living bacteria with large (7.15 Mb) genomes. Therefore, a consistent, quantitative and qualitative description was produced by comparing R. baltica's transcriptional regulator pool with that of 123 publicly available bacterial genomes. The overall results are congruous with earlier observations that in Bacteria, the proportion of genes encoding transcriptional regulators generally increases with genome size. However, R. baltica distinctly stands out from this trend with only 2.4% (174) of all genes predicted to encode transcriptional regulators. The qualitative investigation of R. baltica's transcriptional regulators revealed a clear shift towards high numbers of two-component systems (66) as well as high numbers of sigma factors (49), with more than 76% (37) belonging to the extra-cytoplasmic function subfamily of sigma-70. Only one predicted sigma factor showed a relatively close phylogenetic relationship to that of another bacterium, the sigma factor SigZ of Bacillus subtilis. In summary, analysis of the R. baltica genome revealed disparate regulatory mechanisms and a clear bias towards direct environmental sensing. This strategy might provide a selective advantage for organisms living in habitats with frequently changing environmental conditions.
authors.affiliation: Microbial Genomics Group, Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany.
authors.forename: Thierry
authors.initials: T
authors.lastname: Lombardot
authors.forename: Margarete
authors.initials: M
authors.lastname: Bauer
authors.forename: Hanno
authors.initials: H
authors.lastname: Teeling
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.forename: Frank Oliver
authors.initials: FO
authors.lastname: Glöckner
mesh_terms: D000222:Adaptation, Physiological; D001412:Bacillus subtilis / Q000235:genetics; D001419:Bacteria / Q000145:classification / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D016680:Genome, Bacterial; D010802:Phylogeny; D012808:Sigma Factor / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012808:Sigma Factor; D014157:Transcription Factors