Identification and characterization of a novel “thermophilic-like” Old Yellow Enzyme from the genome of Chryseobacterium sp. CA49

A putative Old Yellow Enzyme (OYE) homologue, Chr-OYE3, was identified from the genome of Chryseobacterium sp. CA49 as a new member of the “thermophilic-like” OYE subfamily. Chr-OYE3 is most closely related to YqjM from Bacillus subtilis with 51% identity. The heterologously expressed enzyme adopted two oligomeric states in solutions, dimers and tetramers. It can reduce a spectrum of activated alkenes, and displayed increased thermal resistance with half-lives of thermal inactivation (t1/2) of 233.5 and 21.8 h at 35 °C and 55 °C, respectively. The enzyme also exhibited high resistance toward various organic solvents, especially water-miscible solvents with higher polarity, such as ethylene glycol and DMSO, which would facilitate its application in biocatalysis where such reaction conditions are often encountered.