Complexes I in the Green Lineage

L. Sazanov (ed.), A Structural Perspective on Respiratory Complex I: Structure and Function of NADH:ubiquinone oxidoreductase, DOI 10.1007/978-94-007-4138-6_11, © Springer Science+Business Media Dordrecht 2012 Abstract In land plants and green algae, mitochondria and chloroplasts were acquired sequentially through primary endosymbiotic events with a a -proteobacterium and a cyanobacterium, respectively. The inner membrane of the mitochondria harbors the enzyme complexes of the respiratory chain, the largest of them being the rotenone-sensitive NADH:ubiquinone oxidoreductase or complex I. In the thylakoid membrane of the chloroplast, besides the photosynthetic machinery, a light-independent respiratory-chain inherited from cyanobacteria drives electrons from NAD(P)H to oxygen. In most plants and algae, it comprises a homolog of bacterial complex I (NAD(P)H:plastoquinone (PQ) oxidoreductase) and a PQ oxidase (PTOX). This chapter will be thus dedicated to similarities and peculiarities of plant mitochondrial complex I compared to the well studied enzyme in mammals and fungi, as well as to the structure and role of a complex I homolog in chloroplast.