The active site structure of the calcium-containing quinoprotein methanol dehydrogenase.
Pyrroloquinoline quinone (PQQ), widely found in nature, serves as the redox cofactor in bacterial methanol dehydrogenase (MEDH), a heterotetrameric enzyme that oxidizes methanol to formaldehyde. The refined structure of MEDH at 2.4-A resolution, based on recently obtained amino acid sequence data, reveals that the PQQ, located in a central channel of the disk-shaped protein, is sandwiched between a Trp side chain and a very unusual vicinal disulfide. A Ca2+ ion forms a bridge between PQQ and the protein molecule, very close to a putative substrate binding pocket. The vicinal disulfide may form during PQQ incorporation and possibly act to hold the latter in place.
White
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Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
Boyd
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G
Mathews
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FS
Xia
Z X
ZX
Dai
W W
WW
Zhang
Y F
YF
Davidson
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VL
D000429:Alcohol Oxidoreductases / Q000648:ultrastructure*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000648:ultrastructure; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000648:ultrastructure; D018360:Crystallography, X-Ray; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D045542:PQQ Cofactor; D017434:Protein Structure, Tertiary; D015363:Quinolones / Q000737:chemistry
D001426:Bacterial Proteins; D002135:Calcium-Binding Proteins; D015363:Quinolones; D045542:PQQ Cofactor; D000429:Alcohol Oxidoreductases; C019641:alcohol dehydrogenase (acceptor)