Essential Role of Acyl-ACP Synthetase in Acclimation of the Cyanobacterium Synechococcus elongatus Strain PCC 7942 to High-Light Conditions

Nobuyuki Takatani, Kazuhide Use, Akihiro Kato, Kazutaka Ikeda, Kouji Kojima, Makiko Aichi, Shin Ichi Maeda, Tatsuo Omata

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Most organisms capable of oxygenic photosynthesis have an aas gene encoding an acyl-acyl carrier protein synthetase (Aas), which activates free fatty acids (FFAs) via esterification to acyl carrier protein. Cyanobacterial aas mutants are often used for studies aimed at photosynthetic production of biofuels because the mutation leads to intracellular accumulation of FFAs and their secretion into the external medium, but the physiological significance of the production of FFAs and their recycling involving Aas has remained unclear. Using an aas-deficient mutant of Synechococcus elongatus strain PCC 7942, we show here that remodeling of membrane lipids is activated by high-intensity light and that the recycling of FFAs is essential for acclimation to high-light conditions. Unlike wild-type cells, the mutant cells could not increase their growth rate as the light intensity was increased from 50 to 400 μmol photons m-2 s-1, and the high-light-grown mutant cells accumulated FFAs and the lysolipids derived from all the four major classes of membrane lipids, revealing high-light-induced lipid deacylation. The high-light-grown mutant cells showed much lower PSII activity and Chl contents as compared with the wild-type cells or low-light-grown mutant cells. The loss of Aas accelerated photodamage of PSII but did not affect the repair process of PSII, indicating that PSII is destabilized in the mutant. Thus, Aas is essential for acclimation of the cyanobacterium to high-light conditions. The relevance of the present finding s to biofuel production using cyanobacteria is discussed.

Original languageEnglish
Pages (from-to)1608-1615
Number of pages8
JournalPlant and Cell Physiology
Volume56
Issue number8
DOIs
Publication statusPublished - 2015 Aug 1
Externally publishedYes

Keywords

  • Acyl-ACP synthetase
  • Biofuel production
  • Cyanobacteria
  • High-light acclimation
  • Photoinhibition of PSII

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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