Research

Characterisation of mitochondrial respiratory-chain components in Chlamydomonas reinhardtii

Respiratory chain in Chlamydomonas comprises four major complexes that transfer electrons from NADH and succinate to molecular oxygen, at least one alternative oxidase and several NAD(P)H dehydrogenases. More than one hundred components of the chain have been identified thanks to the sequencing of the nuclear and mitochondrial genomes of the alga.

The researches of our lab are focusing on the characterization of respiratory components involved in the biogenesis of the complexes. Part of our efforts are devoted to the characterization of complex I. This complex is the less understood of all the enzymes of the respiratory chain, mainly because of its large size. By combining genomic and proteomic approaches, we have identified at least 42 subunits in Chlamydomonas complex I. Except for ND2, all the mitochondria-encoded subunits (ND1, ND4, ND5 and ND6) have been inactivated by random mutagenesis. We are now extending our work to nucleus-encoded subunits that present a particular interest, by using the RNA interference technique to silent the expression of the genes. We are also exploring the biogenesis of complex IV and are trying to elucidate the role of some chaperones involved in the delivery of copper to the enzyme.