TAILIEUCHUNG - Báo cáo khoa học: Agrobacterium tumefaciens type II NADH dehydrogenase Characterization and interactions with bacterial and thylakoid membranes

Type II NADH dehydrogenases (NDH-2) are monomeric enzymes that cat-alyse quinone reduction and allow electrons to enter the respiratory chain in different organisms including higher plant mitochondria, bacteria and yeasts. In this study, anAgrobacterium tumefaciensgene encoding a puta-tive alternative NADH dehydrogenase (AtuNDH-2) was isolated and expressed in Escherichia coli as a (His)6-tagged protein. | ềFEBS Journal Agrobacterium tumefaciens type II NADH dehydrogenase Characterization and interactions with bacterial and thylakoid membranes Laetitia Bernard Carine Desplats Florence Mus Stephan Cuine Laurent Cournac and Gilles Peltier CEA Cadarache Direction des Sciences du Vivant Departement d Ecophysiologie Vegetale et Microbiologie des Bacteries et Microalgues UMR 6191 CNRS-CEA Aix-Marseille II Saint-Paul-lez-Durance France Keywords flavoenzyme type II NADH dehydrogenase plastoquinone reduction quinone reduction respiration Correspondence G. Peltier CEA Cadarache Direction des Sciences du Vivant Departement d Ecophysiologie Vegetale et Microalgues UMR 6191 CNRS-CEA Aix-Marseille II F-13108 Saint-Paul-lez-Durance France Fax 33 442 25 62 65 Tel 33 442 25 76 51 E-mail Present address UMR Microbiologie et Geochimie des sols INRA Universite de Bourgogne Dijon France Department of Plant Biology The Carnegie Institution of Washington Stanford CA USA Note These authors contributed equally to this study Received 4 April2006 revised 16 May 2006 accepted 9 June 2006 doi 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 .

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