Structure of a quinohemoprotein amine dehydrogenase with an uncommon redox cofactor and highly unusual crosslinking
- Saumen Datta*,
- Youichi Mori†,
- Kazuyoshi Takagi‡,§,
- Katsunori Kawaguchi‡,
- Zhi-Wei Chen*,
- Toshihide Okajima†,
- Shun'ichi Kuroda†,
- Tokuji Ikeda‡,
- Kenji Kano‡,
- Katsuyuki Tanizawa†,¶, and
- F. Scott Mathews*,¶,‖
- *Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110; †Department of Structural Molecular Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan; and ‡Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
-
Edited by Perry A. Frey, University of Wisconsin, Madison, WI, and approved October 1, 2001 (received for review August 14, 2001)
Abstract
The crystal structure of the heterotrimeric quinohemoprotein amine dehydrogenase from Paracoccus denitrificans has been determined at 2.05-Å resolution. Within an 82-residue subunit is contained an unusual redox cofactor, cysteine tryptophylquinone (CTQ), consisting of an orthoquinone-modified tryptophan side chain covalently linked to a nearby cysteine side chain. The subunit is surrounded on three sides by a 489-residue, four-domain subunit that includes a diheme cytochrome c. Both subunits sit on the surface of a third subunit, a 337-residue seven-bladed β-propeller that forms part of the enzyme active site. The small catalytic subunit is internally crosslinked by three highly unusual covalent cysteine to aspartic or glutamic acid thioether linkages in addition to the cofactor crossbridge. The catalytic function of the enzyme as well as the biosynthesis of the unusual catalytic subunit is discussed.
Footnotes
-
↵ § Present address: Department of Applied Chemistry, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
-
↵ ¶ K. Tanizawa and F. S. Matthews are both senior authors of this paper.
-
↵ ‖ To whom reprint requests should be addressed. E-mail: mathews{at}biochem.wustl.edu.
-
This paper was submitted directly (Track II) to the PNAS office.
-
Data deposition: The gene sequence and the atomic coordinates of QHNDH have been deposited in GenBank (accession no. AB063330) and the Protein Data Bank, www.rcsb.org (PBD ID code 1JJU), respectively.
- Abbreviations:
- CAO,
- copper amine oxidase;
- CTQ,
- cysteine tryptophylquinone;
- MADH,
- methanol dehydrogenase;
- PQQ,
- pyrroloquinoline quinone;
- QHNDH,
- quinohemoprotein amine dehydrogenase;
- SAM,
- S-adenosylmethionine;
- TPQ,
- topaquinone;
- TTQ,
- tryptophan tryptophylquinone;
- Trq,
- tryptophylquinone;
- ESI,
- electrospray ionization;
- NPH,
- nitrophenylhydrazine
- Copyright © 2001, The National Academy of Sciences
