A novel gene, pmgA, specifically regulates photosystem stoichiometry in the cyanobacterium Synechocystis species PCC 6803 in response to high light

Yukako Hihara, Kintake Sonoike, Masahiko Ikeuchi

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Previously, we identified a novel gene, pmgA, as an essential factor to support photomixotrophic growth of Synechocystis species PCC 6803 and reported that a strain in which pmgA was deleted grew better than the wild type under photoautotrophic conditions. To gain insight into the role of pmgA, we investigated the mutant phenotype of pmgA in detail. When low-light-grown (20 μE m-2 s-1) cells were transferred to high light (HL [200μE m-2 s-1]), pmgA mutants failed to respond in the manner typically associated with Synechocystis. Specifically, mutants lost their ability to suppress accumulation of chlorophyll and photosystem I and, consequently, could not modulate photosystem stoichiometry. These phenotypes seem to result in enhanced rates of photosynthesis and growth during short-term exposure to HL. Moreover, mixed-culture experiments clearly demonstrated that loss of pmgA function was selected against during longer-term exposure to HL, suggesting that pmgA is involved in acquisition of resistance to HL stress. Finally, early induction of pmgA expression detected by reverse transcriptase-PCR upon the shift to HL led us to conclude that pmgA is the first gene identified, to our knowledge, as a specific regulatory factor for H L acclimation.

Original languageEnglish
Pages (from-to)1205-1216
Number of pages12
JournalPlant Physiology
Issue number4
Publication statusPublished - 1998
Externally publishedYes


ASJC Scopus subject areas

  • Plant Science

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