Dataset Information

RpaB, another response regulator operating circadian clock-dependent transcriptional regulation in Synechococcus elongatus PCC 7942.

ABSTRACT: The circadian clock of cyanobacteria is composed of KaiA, KaiB, and KaiC proteins, and the SasA-RpaA two-component system has been implicated in the regulation of one of the output pathways of the clock. In this study, we show that another response regulator that is essential for viability, the RpaA paralog, RpaB, plays a central role in the transcriptional oscillation of clock-regulated genes. In vivo and in vitro analyses revealed that RpaB and not RpaA could specifically bind to the kaiBC promoter, possibly repressing transcription during subjective night. This suggested that binding may be terminated by RpaA to activate gene transcription during subjective day. Moreover, we found that rpoD6 and sigF2, which encode group-2 and group-3 ? factors for RNA polymerase, respectively, were also targets of the RpaAB system, suggesting that a specific group of ? factors can propagate genome-wide transcriptional oscillation. Our findings thus reveal a novel mechanism for a circadian output pathway that is mediated by two paralogous response regulators.

SUBMITTER: Hanaoka M

PROVIDER: S-EPMC3406716 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

RpaB, another response regulator operating circadian clock-dependent transcriptional regulation in Synechococcus elongatus PCC 7942.

Hanaoka Mitsumasa M Takai Naoki N Hosokawa Norimune N Fujiwara Masayuki M Akimoto Yuki Y Kobori Nami N Iwasaki Hideo H Kondo Takao T Tanaka Kan K

The Journal of biological chemistry 20120604 31

The circadian clock of cyanobacteria is composed of KaiA, KaiB, and KaiC proteins, and the SasA-RpaA two-component system has been implicated in the regulation of one of the output pathways of the clock. In this study, we show that another response regulator that is essential for viability, the RpaA paralog, RpaB, plays a central role in the transcriptional oscillation of clock-regulated genes. In vivo and in vitro analyses revealed that RpaB and not RpaA could specifically bind to the kaiBC pro ...[more]

PMID: 22665493

Similar Datasets

Project description:The direct conversion of carbon dioxide into biofuels by photosynthetic microorganisms is a promising alternative energy solution. In this study, a model cyanobacterium, Synechococcus elongatus PCC 7942, is engineered to produce free fatty acids (FFA), potential biodiesel precursors, via gene knockout of the FFA-recycling acyl-ACP synthetase and expression of a thioesterase for release of the FFA. Similar to previous efforts, the engineered strains produce and excrete FFA, but the yields are too low for large-scale production. While other efforts have applied additional metabolic engineering strategies in an attempt to boost FFA production, we focus on characterizing the engineered strains to identify the physiological effects that limit cell growth and FFA synthesis. The strains engineered for FFA-production show reduced photosynthetic yields, chlorophyll-a degradation, and changes in the cellular localization of the light-harvesting pigments, phycocyanin and allophycocyanin. Possible causes of these physiological effects are also identified. The addition of exogenous linolenic acid, a polyunsaturated FFA, to cultures of S. elongatus 7942 yielded a physiological response similar to that observed in the FFA-producing strains with only one notable difference. In addition, the lipid constituents of the cell and thylakoid membranes in the FFA-producing strains show changes in both the relative amounts of lipid components and the degree of saturation of the fatty acid side chains. These changes in lipid composition may affect membrane integrity and structure, the binding and diffusion of phycobilisomes, and the activity of membrane-bound enzymes including those involved in photosynthesis. Thus, the toxicity of unsaturated FFA and changes in membrane composition may be responsible for the physiological effects observed in FFA-producing S. elongatus 7942. These issues must be addressed to enable the high yields of FFA synthesis necessary for large-scale biofuel production.

Dataset Information

RpaB, another response regulator operating circadian clock-dependent transcriptional regulation in Synechococcus elongatus PCC 7942.

Publications

RpaB, another response regulator operating circadian clock-dependent transcriptional regulation in Synechococcus elongatus PCC 7942.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure