US EPA

2167351 

Journal Article 

Crystal structure of cis-biphenyl-2,3-dihydrodiol-2,3-dehydrogenase from a PCB degrader at 2.0 angstrom resolution 

Hulsmeyer, M; Hecht, HJ; Niefind, K; Hofer, B; Eltis, LD; Timmis, KN; Schomburg, D 

1998 

1 

Protein Science
ISSN: 0961-8368
EISSN: 1469-896X 

7 

6 

1286-1293 

WOS:000074208600003 

cis-Biphenyl-2,3-dihydrodiol-2,3-dehydro (BphB) is involved in the aerobic biodegradation of polychlorinated biphenyls (PCBs). The crystal structure of the NAD(+)-enzyme complex was determined by molecular replacement and refined to an R-value of 17.9% at 2.0 Angstrom. As a member of the short-chain alcohol dehydrogenase/reductase (SDR) family, the overall protein fold and positioning of the catalytic triad in BphB are very similar to those observed in other SDR enzymes, although small differences occur in the cofactor binding site. Modeling studies indicate that the substrate is bound in a deep hydrophobic cleft close to the nicotinamide moiety of the NAD(+) cofactor. These studies further suggest that Asn143 is a key determinant of substrate specificity. A two-step reaction mechanism is proposed for cis-dihydrodiol dehydrogenases. 

NAD-dependent oxidoreductase; PCB degradation; short-chain alcohol dehydrogenase; substrate docking; X-ray crystallography