Why is it so difficult to construct Qi site mutants in Chlamydomonas reinhardtii?

Abstract

The cytochrome b6 f complex catalyses electron transfer from plastoquinol to a hydrosoluble acceptor (plastocyanin), while building up an electrochemical proton gradient. Oxidation and reduction of plastoquinol occur respectively at the Qo site (exposed on the luminal side of the thylakoid membrane) and at the Qi site (facing the stroma). The discovery of an additional c′-type heme in the Qi site has cast a new light on the difficulties previously encountered to obtain mutants at this site. In this work, we critically examine our unsuccessful attempts to obtain Qi site mutants based on sequence and structure homology between cytochrome b6 f and bc1 complexes. To cite this article: A. de Lacroix de Lavalette et al., C. R. Biologies 331 (2008). © 2008 Académie des sciences.