Reitz S, Alhapel A, Essen LO, Pierik AJ. Structural and kinetic properties of a beta-hydroxyacid dehydrogenase involved in nicotinate fermentation.
J Mol Biol 2008;
382:802-11. [PMID:
18680749 DOI:
10.1016/j.jmb.2008.07.050]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 07/09/2008] [Accepted: 07/21/2008] [Indexed: 11/17/2022]
Abstract
2-(Hydroxymethyl)glutarate dehydrogenase, the fourth enzyme of the anaerobic nicotinate fermentation pathway of Eubacterium barkeri, catalyzes the NADH-dependent conversion between (S)-2-formylglutarate and (S)-2-(hydroxymethyl)glutarate. As shown by its 2.3-A crystal structure, this enzyme is a novel member of the beta-hydroxyacid dehydrogenase family and adopts a tetrameric architecture with monomers interacting via their C-terminal catalytic domains. The NAD-binding domains protrude heterogeneously from the central, tetrameric core with domain rotation angles differing up to 12 degrees. Kinetic properties of the enzyme, including NADH inhibition constants, were determined. A strong NADH binding in contrast to weaker NAD(+) binding of the protein was inferred from fluorometrically determined binding constants for the dinucleotide cofactor. The data support either an Iso Ordered Bi Bi mechanism or a more common Ordered Bi Bi mechanism as found in other dehydrogenases.
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