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Structure of an acetylating aldehyde dehydrogenase from the thermophilic ethanologen Geobacillus thermoglucosidasius

DOI: 10.1002/pro.3027 DOI Help

Authors: Jonathan Extance (University of Bath) , Michael J. Danson (University of Bath) , Susan J. Crennell (University of Bath)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Protein Science

State: Published (Approved)
Published: August 2016
Diamond Proposal Number(s): 7131

Abstract: Acetylating aldehyde dehydrogenases (AcAldDH) catalyse the acetylation of Coenzyme-A (CoA), or in reverse generate acetaldehyde from Acetyl-CoA using NADH as a co-factor. This paper reports the expression, purification, enzyme assay and X-ray crystal structures of an AcAldDH from Geobacillus thermoglucosidasius (GtAcAldDH) to 2.1Å and in complex with CoA and NAD(+) to 4.0Å. In the structure, the AcAldDH forms a close-knit dimer, similar to that seen in other Alcohol Dehydrogenase (ADH) structures. In GtAcAldDH these dimers associate via their N-termini to form weakly-interacting tetramers. This mode of tetrameric association is also seen in an unpublished AcAldDH deposited in the PDB, but is in contrast to all other ADH structures, (including the one other published AcAldDH found in a bacterial microcompartment), in which the dimers bury a large surface area including the C-termini. This novel mode of association sequesters the active sites and potentially-reactive acyl-enzyme intermediates in the centre of the tetramer. In other respects the structure is very similar to the other AcAldDH, binding the cofactors in a corresponding fashion. This similarity enabled the identification of a shortened substrate cavity in G. thermoglucosidasius AcAldDH, explaining the limitations on the length of substrate accepted by the enzyme.

Journal Keywords: Geobacillus thermoglucosidasius; acetylating aldehyde dehydrogenase; X-ray crystal structure; tetramer; substrate specificity

Diamond Keywords: Bacteria; Enzymes

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography

Other Facilities: no

Added On: 15/09/2016 14:05

Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)