Publication Date:
2014-04-15
Description:
The eubacterial RNA polymerase core, a transcription machinery performing DNA-dependent RNA polymerization, consists of two α subunits and β, β' and subunits. An additional subunit is recruited for promoter recognition and transcription initiation. Cyanobacteria, a group of eubacteria characterized by oxygenic photosynthesis, have a unique composition of the RNA polymerase (RNAP) core due to splitting of the β' subunit to N-terminal and C-terminal β' subunits. The physiological roles of the small subunit of RNAP, encoded by the rpoZ gene, are not yet completely understood in any bacteria. We found that although is non-essential in cyanobacteria, it has a major impact on the overall gene expression pattern. In rpoZ strain, recruitment of the primary factor into the RNAP holoenzyme is inefficient, which causes downregulation of highly expressed genes and upregulation of many low-expression genes. Especially, genes encoding proteins of photosynthetic carbon concentrating and carbon fixing complexes were down, and the rpoZ mutant showed low light-saturated photosynthetic activity and accumulated photoprotective carotenoids and α-tocopherol. The results indicate that the subunit facilitates the association of the primary factor with the RNAP core, thereby allowing efficient transcription of highly expressed genes.
Print ISSN:
0305-1048
Electronic ISSN:
1362-4962
Topics:
Biology
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