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Interdependent expression of the ccoNOQP-rdxBHIS loci in Rhodobacter sphaeroides 2.4.1.

ABSTRACT: The rdxBHIS gene cluster of Rhodobacter sphaeroides 2.4.1, located downstream of the ccoNOQP operon encoding the cbb(3) cytochrome c oxidase, is required for the posttranscriptional modification of the cbb(3) cytochrome c oxidase. The cbb(3) cytochrome c oxidase is the main terminal oxidase under microaerobic conditions, as well as a component of the signal transduction pathway controlling photosynthesis gene expression. Because of the intimate functional and positional relationships of the ccoNOQP operon and the rdxBHIS gene cluster, we have examined the transcriptional activities of this DNA region in order to understand their expression and regulation. Northern blot analysis and reverse transcription-PCR, together with earlier complementation analysis, suggested that the ccoNOQP-rdxBHIS cluster is transcribed as ccoNOQP-, ccoNOQP-rdxBH-, rdxBH-, and rdxIS-specific transcripts. Multiple transcriptional start sites have been identified by primer extension analyses: five for ccoN, four for rdxB, and one for rdxI. Transcription from P1(N) of ccoN and P1(B) of rdxB is dependent on the presence of FnrL. LacZ fusion analysis support the above-described studies, especially the importance of FnrL. Expression of the cco-rdx cluster is closely related to photosynthesis gene expression, suggesting that transcript stoichiometry and presumably the stoichiometry of the gene products are critical factors in controlling photosynthesis gene expression.

SUBMITTER: Roh JH

PROVIDER: S-EPMC135364 | biostudies-literature | 2002 Oct

REPOSITORIES: biostudies-literature

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Interdependent expression of the ccoNOQP-rdxBHIS loci in Rhodobacter sphaeroides 2.4.1.

Roh Jung Hyeob JH Kaplan Samuel S

Journal of bacteriology 20021001 19

The rdxBHIS gene cluster of Rhodobacter sphaeroides 2.4.1, located downstream of the ccoNOQP operon encoding the cbb(3) cytochrome c oxidase, is required for the posttranscriptional modification of the cbb(3) cytochrome c oxidase. The cbb(3) cytochrome c oxidase is the main terminal oxidase under microaerobic conditions, as well as a component of the signal transduction pathway controlling photosynthesis gene expression. Because of the intimate functional and positional relationships of the ccoN ...[more]

PMID: 12218019

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Project description:BackgroundRhodobacter sphaeroides 2.4.1 is a metabolically versatile organism that belongs to ?-3 subdivision of Proteobacteria. The present study was to identify the extent, history, and role of gene duplications in R. sphaeroides 2.4.1, an organism that possesses two chromosomes.ResultsA protein similarity search (BLASTP) identified 1247 orfs (~29.4% of the total protein coding orfs) that are present in 2 or more copies, 37.5% (234 gene-pairs) of which exist in duplicate copies. The distribution of the duplicate gene-pairs in all Clusters of Orthologous Groups (COGs) differed significantly when compared to the COG distribution across the whole genome. Location plots revealed clusters of gene duplications that possessed the same COG classification. Phylogenetic analyses were performed to determine a tree topology predicting either a Type-A or Type-B phylogenetic relationship. A Type-A phylogenetic relationship shows that a copy of the protein-pair matches more with an ortholog from a species closely related to R. sphaeroides while a Type-B relationship predicts the highest match between both copies of the R. sphaeroides protein-pair. The results revealed that ~77% of the proteins exhibited a Type-A phylogenetic relationship demonstrating the ancient origin of these gene duplications. Additional analyses on three other strains of R. sphaeroides revealed varying levels of gene loss and retention in these strains. Also, analyses on common gene pairs among the four strains revealed that these genes experience similar functional constraints and undergo purifying selection.ConclusionsAlthough the results suggest that the level of gene duplication in organisms with complex genome structuring (more than one chromosome) seems to be not markedly different from that in organisms with only a single chromosome, these duplications may have aided in genome reorganization in this group of eubacteria prior to the formation of R. sphaeroides as gene duplications involved in specialized functions might have contributed to complex genomic development.

Dataset Information

Interdependent expression of the ccoNOQP-rdxBHIS loci in Rhodobacter sphaeroides 2.4.1.

Publications

Interdependent expression of the ccoNOQP-rdxBHIS loci in Rhodobacter sphaeroides 2.4.1.

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