tailieunhanh - Báo cáo khoa học: Hexameric ring structure of a thermophilic archaeon NADH oxidase that produces predominantly H2O

Saccharomyces cerevisiaeis known to be able to adapt to the presence of the commonly used food preservative benzoic acid with a large energy expenditure. Some mechanisms for the adaptation process have been sug-gested, but its quantitative energetic and metabolic aspects have rarely been discussed. | ỊFEBS Journal Hexameric ring structure of a thermophilic archaeon NADH oxidase that produces predominantly H2O Baolei Jia1 Seong-Cheol Park1 1 Sangmin Lee1 Bang P. Pham1 Rui Yu1 Thuy L. Le1 Sang Woo Han2 3 Jae-Kyung Yang4 Myung-Suk Choi4 Wolfgang Baumeister5 and Gang-Won Cheong1 3 1 Division of Applied Life Sciences BK21 Program Gyeongsang National university Jinju Korea 2 Department of Chemistry Research Institute of NaturalScience Gyeongsang NationalUniversity Jinju Korea 3 EnvironmentalBiotechnology NationalCore Research Center Gyeongsang NationalUniversity Jinju Korea 4 Division of EnvironmentalForest Science and Institute of Agriculture and Life Science Gyeongsang NationalUniversity Jinju Korea 5 Department of Molecular StructuralBiology Max-Planck-Institute for Biochemistry Martinsried Germany Keywords electron microscopy H2O-producing hexameric ring structure NADH oxidase thermophilic archaeon Correspondence . Cheong Division of Applied Life Sciences Gyeongsang NationalUniversity Jinju 660-701 Korea Fax 82 55 752 7062 Tel 82 55 751 5962 E-mail gwcheong@ TPresent address Research Center for Proteineous Materials Chosun University Kwangju 501-759 Korea These authors contributed equally to this work An NADH oxidase NOX was cloned from the genome of Thermococcus profundus NOXtp by genome walking and the encoded protein was purified to homogeneity after expression in Escherichia coli. Subsequent analyses showed that it is an FAD-containing protein with a subunit molecular mass of 49 kDa that exists as a hexamer with a native molecular mass of 300 kDa. A ring-shaped hexameric form was revealed by electron microscopic and image processing analyses. NOXtp catalyzed the oxidization of NADH and NADPH and predominantly converted O2 to H2O but not to H2O2 as in the case of most other NOX enzymess. To our knowledge this is the first example of a NOX that can produce H2O predominantly in a thermophilic organism. As an enzyme with two cysteine residues NOXtp .