A pH-dependent shift of redox cofactor specificity in a benzyl alcohol dehydrogenase of aromatoleum aromaticum EbN1

• Published in: Applied microbiology and biotechnology 2024-12, Vol.108 (1), p.410, Article 410
• Main Authors: Gemmecker, Yvonne, Winiarska, Agnieszka, Hege, Dominik, Kahnt, Jörg, Seubert, Andreas, Szaleniec, Maciej, Heider, Johann
• Format: Article
• Language: English
• Subjects: Alcohol; Alcohol dehydrogenase; Alcohol Oxidoreductases - chemistry; Alcohol Oxidoreductases - genetics; Alcohol Oxidoreductases - metabolism; Alcohols; Aldehydes; Benzaldehyde; Benzaldehydes - chemistry; Benzaldehydes - metabolism; Benzoates; Benzoic acid; Benzyl alcohol; Benzyl Alcohol - chemistry; Benzyl Alcohol - metabolism; Binding Sites; Biomedical and Life Sciences; Biotechnologically Relevant Enzymes and Proteins; Biotechnology; Carbonyl compounds; Carbonyl groups; Carbonyls; Cascade chemical reactions; Catalytic Domain; Coenzymes - metabolism; Dehydrogenase; Dehydrogenases; Enzymes; Histidine; Hydrogen-Ion Concentration; Iron; Kinetics; Life Sciences; Microbial Genetics and Genomics; Microbiology; Models, Molecular; NAD - metabolism; NADP - metabolism; Oxidation-Reduction; pH effects; Phylogeny; Structural models; Substrate Specificity; Substrates; Tungsten; Zinc; Zinc - metabolism
• ISSN: 0175-7598; 1432-0614; 1432-0614
• DOI: 10.1007/s00253-024-13225-z

We characterise a reversible bacterial zinc-containing benzyl alcohol dehydrogenase (BaDH) accepting either NAD + or NADP + as a redox cofactor. Remarkably, its redox cofactor specificity is pH-dependent with the phosphorylated cofactors favored at lower and the dephospho-forms at higher pH. BaDH also shows different steady-state kinetic behavior with the two cofactor forms. From a structural model, the pH-dependent shift may affect the charge of a histidine in the 2′-phosphate-binding pocket of the redox cofactor binding site. The enzyme is phylogenetically affiliated to a new subbranch of the Zn-containing alcohol dehydrogenases, which share this conserved residue. BaDH appears to have some specificity for its substrate, but also turns over many substituted benzyl alcohol and benzaldehyde variants, as well as compounds containing a conjugated C=C double bond with the aldehyde carbonyl group. However, compounds with an sp 3 -hybridised C next to the alcohol/aldehyde group are not or only weakly turned over. The enzyme appears to contain a Zn in its catalytic site and a mixture of Zn and Fe in its structural metal-binding site. Moreover, we demonstrate the use of BaDH in an enzyme cascade reaction with an acid-reducing tungsten enzyme to reduce benzoate to benzyl alcohol. Key points •Zn-containing BaDH has activity with either NAD + or NADP + at different pH optima. •BaDH converts a broad range of substrates. •BaDH is used in a cascade reaction for the reduction of benzoate to benzyl alcohol.