Structural highlights
Publication Abstract from PubMedThe 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 [Wohlbrand 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 A, 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 (Phe187), contrasting the (S)-specificity of previously reported 1-phenylethanol dehydrogenase (Ped; Tyr93) from strain EbN1 [Hoffken et al: Biochemistry 2006;45:82-93]. Molecular Genetic and Crystal Structural Analysis of 1-(4-Hydroxyphenyl)-Ethanol Dehydrogenase from 'Aromatoleum aromaticum' EbN1.,Busing I, Hoffken HW, Breuer M, Wohlbrand L, Hauer B, Rabus R J Mol Microbiol Biotechnol. 2015;25(5):327-39. doi: 10.1159/000439113. Epub 2015 , Oct 22. PMID:26488297[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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