Discovery of a novel (R)-selective bacterial hydroxynitrile lyase from Acidobacterium capsulatum

Romana Wiedner; Mandana Gruber-Khadjawi; Helmut Schwab; Kerstin Steiner

doi:10.1016/j.csbj.2014.07.002

Discovery of a novel (R)-selective bacterial hydroxynitrile lyase from Acidobacterium capsulatum

Comput Struct Biotechnol J. 2014 Jul 8;10(16):58-62. doi: 10.1016/j.csbj.2014.07.002. eCollection 2014 Jun.

Authors

Romana Wiedner¹, Mandana Gruber-Khadjawi¹, Helmut Schwab², Kerstin Steiner¹

Affiliations

¹ ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria.
² ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria ; Institute of Molecular Biotechnology, TU Graz, Petersgasse 14/5, 8010 Graz, Austria.

Abstract

Hydroxynitrile lyases (HNLs) are powerful carbon-carbon bond forming enzymes. The reverse of their natural reaction - the stereoselective addition of hydrogen cyanide (HCN) to carbonyls - yields chiral cyanohydrins, versatile building blocks for the pharmaceutical and chemical industry. Recently, bacterial HNLs have been discovered, which represent a completely new type: HNLs with a cupin fold. Due to various benefits of cupins (e.g. high yield recombinant expression in Escherichia coli), the class of cupin HNLs provides a new source for interesting, powerful hydroxynitrile lyases in the ongoing search for HNLs with improved activity, enantioselectivity, stability and substrate scope. In this study, database mining revealed a novel cupin HNL from Acidobacterium capsulatum ATCC 51196 (AcHNL), which was able to catalyse the (R)-selective synthesis of mandelonitrile with significantly better conversion (97%) and enantioselectivity (96.7%) than other cupin HNLs.

Keywords: Biocatalysis; Cyanohydrin synthesis; Hydroxynitrile lyase; Mandelonitrile; Manganese-dependent HNL.