title: Oxidative phosphorylation in a thermophilic, facultative chemoautotroph, Hydrogenophilus thermoluteolus, living prevalently in geothermal niches.
abstract: Hydrogenophilus is a thermophilic, facultative chemoautotroph, which lives prevalently in high temperature geothermal niches. Despite the environmental distribution, little is known about its oxidative phosphorylation. Here, we show that inverted membrane vesicles derived from Hydrogenophilus thermoluteolus cells autotrophically cultivated with H2 formed a proton gradient on the addition of succinate, dl-lactate, and NADH, and exhibited oxidation activity toward these three organic compounds. These indicate the capability of mixotrophic growth of this bacterium. Biochemical analysis demonstrated that the same vesicles contained an F-type ATP synthase. The F1 sector of the ATP synthase purified from H. thermoluteolus membranes exhibited optimal ATPase activity at 65°C. Transformed Escherichia coli membranes expressing H. thermoluteolus F-type ATP synthase exhibited the same temperature optimum for the ATPase. These findings shed light on H. thermoluteolus oxidative phosphorylation from the aspects of membrane bioenergetics and ATPase biochemistry, which must be fundamental and advantageous in the biogeochemical cycles occurred in the high temperature geothermal niches.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakai
authors.forename: Misa
authors.initials: M
authors.lastname: Masanari
authors.forename: Takumi
authors.initials: T
authors.lastname: Ikeda
authors.forename: Naho
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: Saori
authors.initials: S
authors.lastname: Ueshima
authors.forename: Kaori
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nishihara
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sambongi
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology; D052837:Chemoautotrophic Growth; D017753:Ecosystem; D006358:Hot Temperature; D006859:Hydrogen / Q000378:metabolism; D043363:Hydrogenophilaceae / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010085:Oxidative Phosphorylation
chemical_list: D001426:Bacterial Proteins; D006859:Hydrogen; D000251:Adenosine Triphosphatases