Photosynthetic control of chloroplast gene expression

• DOI: 10.1038/17624
• Publication Date: 2002-07-26T08:39:18Z
• Authors: Thomas Pfannschmidt; Anders Nilsson; John F. Allen
• Keywords: 0303 health sciences; 03 medical and health sciences

Redox chemistry—the transfer of electrons or hydrogen atoms—is central to energy conversion in respiration and photosynthesis. In photosynthesis in chloroplasts, two separate, light-driven reactions, termed photosystem I and photosystem II, are connected in series by a chain of electron carriers1,2,3. The redox state of one connecting electron carrier, plastoquinone, governs the distribution of absorbed light energy between photosystems I and II by controlling the phosphorylation of a mobile, light-harvesting, pigment–protein complex4,5. Here we show that the redox state of plastoquinone also controls the rate of transcription of genes encoding reaction-centre apoproteins of photosystem I and photosystem II. As a result of this control, the stoichiometry between the two photosystems changes in a way that counteracts the inefficiency produced when either photosystem limits the rate of the other. In eukaryotes, these reaction-centre proteins are encoded universally within the chloroplast. Photosynthetic control of chloroplast gene expression indicates an evolutionary explanation for this rule: the redox signal-transduction pathway can be short, the response rapid, and the control direct.