FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in synechocystis sp. pcc 6803 under CO2-limited conditions

Ginga Shimakawa, Keiichiro Shaku, Akiko Nishi, Ryosuke Hayashi, Hiroshi Yamamoto, Katsuhiko Sakamoto, Amane Makino, Chikahiro Miyake

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2- limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADHdependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2are not available.

Original languageEnglish
Pages (from-to)472-480
Number of pages9
JournalPlant physiology
Volume167
Issue number2
DOIs
Publication statusPublished - 2015 Jan 1

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

Fingerprint Dive into the research topics of 'FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in synechocystis sp. pcc 6803 under CO<sub>2</sub>-limited conditions'. Together they form a unique fingerprint.

Cite this