title: Agrobacterium tumefaciens type II NADH dehydrogenase. Characterization and interactions with bacterial and thylakoid membranes.
abstract: Type II NADH dehydrogenases (NDH-2) are monomeric enzymes that catalyse quinone reduction and allow electrons to enter the respiratory chain in different organisms including higher plant mitochondria, bacteria and yeasts. In this study, an Agrobacterium tumefaciens gene encoding a putative alternative NADH dehydrogenase (AtuNDH-2) was isolated and expressed in Escherichia coli as a (His)6-tagged protein. The purified 46 kDa protein contains FAD as a prosthetic group and oxidizes both NADH and NADPH with similar Vmax values, but with a much higher affinity for NADH than for NADPH. AtuNDH-2 complements the growth (on a minimal medium) of an E. coli mutant strain deficient in both NDH-1 and NDH-2, and is shown to supply electrons to the respiratory chain when incubated with bacterial membranes prepared from this mutant. By measuring photosystem II chlorophyll fluorescence on thylakoid membranes prepared from the green alga Chlamydomonas reinhardtii, we show that AtuNDH-2 is able to stimulate NADH-dependent reduction of the plastoquinone pool. We discuss the possibility of using heterologous expression of NDH-2 enzymes to improve nonphotochemical reduction of plastoquinones and H2 production in C. reinhardtii.
authors.affiliation: CEA Cadarache, Direction des Sciences du Vivant, Département d'Ecophysiologie Végétale et Microbiologie, Laboratoire de Bioénergétique et Biotechnologie [corrected] des Bactéries et Microalgues, UMR 6191 CNRS-CEA, Aix-Marseille II [corrected] France.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Bernard
authors.forename: Carine
authors.initials: C
authors.lastname: Desplats
authors.forename: Florence
authors.initials: F
authors.lastname: Mus
authors.forename: Stéphan
authors.initials: S
authors.lastname: Cuiné
authors.forename: Laurent
authors.initials: L
authors.lastname: Cournac
authors.forename: Gilles
authors.initials: G
authors.lastname: Peltier
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology*; D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D009245:NADH Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D009245:NADH Dehydrogenase