Atomic resolution structures of R-specific alcohol dehydrogenase from Lactobacillus brevis provide the structural bases of its substrate and cosubstrate specificity.

Article Details

Citation

Copy to clipboard

Schlieben NH, Niefind K, Muller J, Riebel B, Hummel W, Schomburg D

Atomic resolution structures of R-specific alcohol dehydrogenase from Lactobacillus brevis provide the structural bases of its substrate and cosubstrate specificity.

J Mol Biol. 2005 Jun 17;349(4):801-13.

PubMed ID

15896805 [ View in PubMed

]

Abstract

The R-specific alcohol dehydrogenase (RADH) from Lactobacillus brevis is an NADP-dependent, homotetrameric member of the extended enzyme family of short-chain dehydrogenases/reductases (SDR) with a high biotechnological application potential. Its preferred in vitro substrates are prochiral ketones like acetophenone with almost invariably a small methyl group as one substituent and a bulky (often aromatic) moiety as the other. On the basis of an atomic-resolution structure of wild-type RADH in complex with NADP and acetophenone, we designed the mutant RADH-G37D, which should possess an improved cosubstrate specificity profile for biotechnological purposes, namely, a preference for NAD rather than NADP. Comparative kinetic measurements with wild-type and mutant RADH showed that this aim was achieved. To characterize the successful mutant structurally, we determined several, partly atomic-resolution, crystal structures of RADH-G37D both as an apo-enzyme and as ternary complex with NAD or NADH and phenylethanol. The increased affinity of RADH-G37D for NAD(H) depends on an interaction between the adenosine ribose moiety of NAD and the inserted aspartate side-chain. A structural comparison between RADH-G37D as apo-enzyme and as a part of a ternary complex revealed significant rearrangements of Ser141, Glu144, Tyr189 and Met205 in the vicinity of the active site. This plasticity contributes to generate a small hydrophobic pocket for the methyl group typical for RADH substrates, and a hydrophobic coat for the second, more variable and often aromatic, substituent. Around Ser141 we even found alternative conformations in the backbone. A structural adaptability in this region, which we describe here for the first time for an SDR enzyme, is probably functionally important, because it concerns Ser142, a member of the highly conserved catalytic tetrad typical for SDR enzymes. Moreover, it affects an extended proton relay system that has been identified recently as a critical element for the catalytic mechanism in SDR enzymes.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
(R)-1-phenylethanol	R-specific alcohol dehydrogenase	Protein	Lactobacillus brevis	Unknown	Not Available	Details

Polypeptides

Name	UniProt ID
R-specific alcohol dehydrogenase	Q84EX5	Details