Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
, 355 (1402), 1351-9

Balancing the Two Photosystems: Photosynthetic Electron Transfer Governs Transcription of Reaction Centre Genes in Chloroplasts

Affiliations
Review

Balancing the Two Photosystems: Photosynthetic Electron Transfer Governs Transcription of Reaction Centre Genes in Chloroplasts

J F Allen et al. Philos Trans R Soc Lond B Biol Sci.

Abstract

Chloroplasts are cytoplasmic organelles whose primary function is photosynthesis, but which also contain small, specialized and quasi-autonomous genetic systems. In photosynthesis, two energy converting photosystems are connected, electrochemically, in series. The connecting electron carriers are oxidized by photosystem I (PS I) and reduced by photosystem II (PS II). It has recently been shown that the oxidation reduction state of one connecting electron carrier, plastoquinone, controls transcription of chloroplast genes for reaction centre proteins of the two photosystems. The control counteracts the imbalance in electron transport that causes it: oxidized plastoquinone induces PS II and represses PS I; reduced plastoquinone induces PS I and represses PS II. This complementarity is observed both in vivo, using light favouring one or other photosystem, and in vitro, when site-specific electron transport inhibitors are added to transcriptionally and photosynthetically active chloroplasts. There is thus a transcriptional level of control that has a regulatory function similar to that of purely post-translational 'state transitions' in which the redistribution of absorbed excitation energy between photosystems is mediated by thylakoid membrane protein phosphorylation. The changes in rates of transcription that are induced by spectral changes in vivo can be detected even before the corresponding state transitions are complete, suggesting the operation of a branched pathway of redox signal transduction. These findings suggest a mechanism for adjustment of photosystem stoichiometry in which initial events involve a sensor of the redox state of plastoquinone, and may thus be the same as the initial events of state transitions. Redox control of chloroplast transcription is also consistent with the proposal that a direct regulatory coupling between electron transport and gene expression determines the function and composition of the chloroplast's extra-nuclear genetic system.

Similar articles

See all similar articles

Cited by 44 articles

See all "Cited by" articles

References

    1. Ann N Y Acad Sci. 1987;503:55-71 - PubMed
    1. FEBS Lett. 1990 May 7;264(1):25-8 - PubMed
    1. Biochim Biophys Acta. 1969 Feb 25;172(2):242-51 - PubMed
    1. Nature. 1998 Mar 5;392(6671):37-41 - PubMed
    1. Biochim Biophys Acta. 1973 Dec 14;325(3):573-85 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources

Feedback