O2-dependent large electron flow functioned as an electron sink, replacing the steady-state electron flux in photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, but not in the cyanobacterium Synechococcus sp. PCC 7942

Ryosuke Hayashi, Ginga Shimakawa, Keiichiro Shaku, Satoko Shimizu, Seiji Akimoto, Hiroshi Yamamoto, Katsumi Amako, Toshio Sugimoto, Masahiro Tamoi, Amane Makino, Chikahiro Miyake

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    To determine whether alternative electron flow (AEF) can replace the photosynthetic electron flow in cyanobacteria, we used an open O2-electrode system to monitor O2-exchange over a long period. In air-grown Synechocystis sp. PCC 6803 (S. 6803 (WT)), the quantum yield of PSII, Y(II), held even after photosynthesis was suppressed by CO2 shortage. The S. 6803 mutant, deficient in flavodiiron (FLV) proteins 1 and 3, showed the same phenotype as S. 6803(WT). In contrast, Y(II) decreased in Synechococcus sp. PCC 7942 (S. 7942). These results suggest that AEF functioned as the Y(II) in S. 6803 and replaced the photosynthetic electron flux. In contrast, the activity of AEF in S. 7942 was lower. The affinity of AEF for O2 in S. 6803 did not correspond to those of FLVs in bacteria or terminal oxidases in respiration. AEF might be driven by photorespiration.

    Original languageEnglish
    Pages (from-to)384-393
    Number of pages10
    JournalBioscience, Biotechnology and Biochemistry
    Volume78
    Issue number3
    DOIs
    Publication statusPublished - 2014

    Keywords

    • Alternative electron flow
    • Cyanobacteria
    • Oxygen
    • Photorespiration
    • Photosynthesis

    ASJC Scopus subject areas

    • Biotechnology
    • Analytical Chemistry
    • Biochemistry
    • Applied Microbiology and Biotechnology
    • Molecular Biology
    • Organic Chemistry

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