title: Structural biology. Division of labor in transhydrogenase by alternating proton translocation and hydride transfer.
abstract: NADPH/NADP(+) (the reduced form of NADP(+)/nicotinamide adenine dinucleotide phosphate) homeostasis is critical for countering oxidative stress in cells. Nicotinamide nucleotide transhydrogenase (TH), a membrane enzyme present in both bacteria and mitochondria, couples the proton motive force to the generation of NADPH. We present the 2.8 Å crystal structure of the transmembrane proton channel domain of TH from Thermus thermophilus and the 6.9 Å crystal structure of the entire enzyme (holo-TH). The membrane domain crystallized as a symmetric dimer, with each protomer containing a putative proton channel. The holo-TH is a highly asymmetric dimer with the NADP(H)-binding domain (dIII) in two different orientations. This unusual arrangement suggests a catalytic mechanism in which the two copies of dIII alternatively function in proton translocation and hydride transfer.
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Josephine H
authors.initials: JH
authors.lastname: Leung
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Lici A
authors.initials: LA
authors.lastname: Schurig-Briccio
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Arne
authors.initials: A
authors.lastname: Moeller
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Speir
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Gennis
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. dave@scripps.edu.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Stout
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D009250:NADP Transhydrogenases / Q000737:chemistry*; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D011522:Protons; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D011522:Protons; D009250:NADP Transhydrogenases