Regulation of cytochrome f expression

Y. Choquet, C. Raynaud, C. Loiselay, B. Derrien, A. Boulouis, J. Girard-Bascou and F.-A. Wollman

UMR7141, Intitut de Biologie Physico-Chimique, 13, rue Pierre et Marie Curie, F-75005 Paris, France

A salient feature of organelle gene expression is the requirement for nucleus-encoded factors that act post-transcriptionally in a gene specific manner. The chloroplast petA gene encoding cytochrome f, a major subunit of the cytochrome b6f complex, is a typical example as its expression depends on two specific nucleus-encoded factors: MCA1, required for stable accumulation of the petA transcript and TCA1, required for its translation. We have investigated the role of these two factors. TCA1 and MCA1 act on distinct but neighbouring targets in the petA 5' UTR, interact together and their action on cytochrome f expression is cooperative. These two factors, together with the petA transcript, constitute the cytochrome f expression system. We present data on the role of TCA1 and MCA1 in the regulation of cytochrome f expression.

e-mail address of presenting author: choquet@ibpc.fr