期刊
ISME JOURNAL
卷 5, 期 10, 页码 1641-1651出版社
SPRINGERNATURE
DOI: 10.1038/ismej.2011.36
关键词
flavobacteria; marine; photoheterotrophy; proteorhodopsin; transcriptomics
资金
- Gordon and Betty Moore Foundation
- Office of Science
- US Department of Energy
- NSF Science and Technology Center [EF0424599]
- Japan Society for the Promotion of Science (JSPS)
- Grants-in-Aid for Scientific Research [23657016] Funding Source: KAKEN
Proteorhodopsin (PR) is a photoprotein that functions as a light-driven proton pump in diverse marine Bacteria and Archaea. Recent studies have suggested that PR may enhance both growth rate and yield in some flavobacteria when grown under nutrient-limiting conditions in the light. The direct involvement of PR, and the metabolic details enabling light-stimulated growth, however, remain uncertain. Here, we surveyed transcriptional and growth responses of a PR-containing marine flavobacterium during carbon-limited growth in the light and the dark. As previously reported (Gomez-Consarnau et al., 2007), Dokdonia strain MED134 exhibited light-enhanced growth rates and cell yields under low carbon growth conditions. Inhibition of retinal biosynthesis abolished the light-stimulated growth response, supporting a direct role for retinal-bound PR in light-enhanced growth. Among protein-coding transcripts, both PR and retinal biosynthetic enzymes showed significant upregulation in the light. Other light-associated proteins, including bacterial cryptochrome and DNA photolyase, were also expressed at significantly higher levels in the light. Membrane transporters for Na+/phosphate and Na+/alanine symporters, and the Na+-translocating NADH-quinone oxidoreductase (NQR) linked electron transport chain, were also significantly upregulated in the light. Culture experiments using a specific inhibitor of Na+-translocating NQR indicated that sodium pumping via NQR is a critical metabolic process in the light-stimulated growth of MED134. In total, the results suggested the importance of both the PR-enabled, light-driven proton gradient, as well as the generation of a Na+ ion gradient, as essential components for light-enhanced growth in these flavobacteria. The ISME Journal (2011) 5, 1641-1651; doi:10.1038/ismej.2011.36; published online 7 April 2011
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