title: Structural and sequence comparisons of quinone oxidoreductase, zeta-crystallin, and glucose and alcohol dehydrogenases.
abstract: Quinone oxidoreductase, zeta-crystallin, glucose dehydrogenase, and alcohol dehydrogenase belong to a superfamily of medium-chain dehydrogenase/reductases. The crystal structures of Escherichia coli quinone oxidoreductase (QOR) and Thermoplasma acidophilum glucose dehydrogenase have recently been determined and are compared here with the well-known structure of horse liver alcohol dehydrogenase. A structurally based comparison of these three enzymes confirms that they possess extensive overall structural homology despite low sequence identity. The most significant difference is the absence of the catalytic and structural zinc ions in QOR. A multiple structure-based sequence alignment has been constructed for the three enzymes and extended to include zeta-crystallin, an eye lens structural protein with quinone oxidoreductase activity and high sequence identity to E. coli quinone oxidoreductase. Residues which are important for catalysis have been altered and the functions and activities of the enzymes have diverged, illustrating a classic example of divergent evolution among a superfamily of enzymes.
authors.affiliation: Centre for Molecular Structure and Function, Research School of Chemistry, Australian National University, Canberra, Australia.
authors.forename: K J
authors.initials: KJ
authors.lastname: Edwards
authors.forename: J D
authors.initials: JD
authors.lastname: Barton
authors.forename: J
authors.initials: J
authors.lastname: Rossjohn
authors.forename: J M
authors.initials: JM
authors.lastname: Thorn
authors.forename: G L
authors.initials: GL
authors.lastname: Taylor
authors.forename: D L
authors.initials: DL
authors.lastname: Ollis
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D003459:Crystallins / Q000737:chemistry* / Q000235:genetics; D042843:Glucose 1-Dehydrogenase; D005948:Glucose Dehydrogenases / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D011487:Protein Conformation; D011808:Quinone Reductases / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment / Q000379:methods; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
chemical_list: D003459:Crystallins; D009243:NAD; D009249:NADP; D005948:Glucose Dehydrogenases; D000426:Alcohol Dehydrogenase; D042843:Glucose 1-Dehydrogenase; D011808:Quinone Reductases