Molecular Genetic and Crystal Structural Analysis of 1-(4-Hydroxyphenyl)-Ethanol Dehydrogenase from 'Aromatoleum Aromaticum' Ebn1.Busing, I., Hoffken, H.W., Breuer, M., Wohlbrand, L., Hauer, B., Rabus, R.
(2015) J Mol Microbiol Biotechnol 25: 327
- PubMed: 26488297
- DOI: https://doi.org/10.1159/000439113
- Primary Citation of Related Structures:
- PubMed Abstract:
The dehydrogenation of 1-(4-hydroxyphenyl)-ethanol to 4-hydroxyacetophenone represents the second reaction step during anaerobic degradation of p-ethylphenol in the denitrifying bacterium 'Aromatoleum aromaticum' EbN1. Previous proteogenomic studies identified two different proteins (ChnA and EbA309) as possible candidates for catalyzing this reaction [Wöhlbrand et al: J Bacteriol 2008;190:5699-5709]. Physiological-molecular characterization of newly generated unmarked in-frame deletion and complementation mutants allowed defining ChnA (renamed here as Hped) as the enzyme responsible for 1-(4-hydroxyphenyl)-ethanol oxidation. Hped [1-(4-hydroxyphenyl)-ethanol dehydrogenase] belongs to the 'classical' family within the short-chain alcohol dehydrogenase/reductase (SDR) superfamily. Hped was overproduced in Escherichia coli, purified and crystallized. The X-ray structures of the apo- and NAD(+)-soaked form were resolved at 1.5 and 1.1 Å, respectively, and revealed Hped as a typical homotetrameric SDR. Modeling of the substrate 4-hydroxyacetophenone (reductive direction of Hped) into the active site revealed the structural determinants of the strict (R)-specificity of Hped (Phe(187)), contrasting the (S)-specificity of previously reported 1-phenylethanol dehydrogenase (Ped; Tyr(93)) from strain EbN1 [Höffken et al: Biochemistry 2006;45:82-93].
Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Oldenburg, Germany.