Journal of Bioscience and Bioengineering, Vol.129, No.1, 13-21, 2019
Expression of alcohol oxidase gene from Ochrobactrum sp. AIU 033 in recombinant Escherichia coli through the twin-arginine translocation pathway
We cloned a set of genes encoding alcohol oxidase from Ochrobactrum sp. MU 033 (OcAOD), which exhibits the appropriate substrate specificity for glyoxylic acid production from glycolic acid. The set of genes for OcAOD contained two open reading frames consisting of 555-bp (aodB) and 1572-bp (aodA) nucleotides, which encode the precursor for the beta-subunit and alpha-subunit of OcAOD, respectively. We expressed the cloned genes as an active product in Escherichia con BL21(DE3). The recombinant OcAOD oxidized glycolic acid and primary alcohols with C2-C8 but not glyoxylic acid (as is the case for native OcAOD), whereas the K-m and V-max values for glycolic acid and the pH stability were higher than those of native OcAOD. A consensus sequence for the twin-arginine translocation (Tat) pathway was identified in the N-terminal region of the precursor for the beta-subunit, and the active form of OcAOD was localized in the periplasm of recombinant E. coli, which indicated that OcAOD would be transported from the cytoplasm to the periplasm by the hitchhiker mechanism through the Tat pathway. The OcAOD productivity of the recombinant E. coli was 24-fold higher than that of Ochrobactrum sp. AIU 033, and it was further enhanced by 1.2 times by the co-expression of additional tatABC from E. coli BL21(DE3). Our findings thus suggest a function of the beta-subunit of OcAOD in membrane trans location, and that the recombinant OcAOD has characteristics that are suitable for the enzymatic synthesis of glyoxylic acid as well as native OcAOD. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.
Keywords:Alcohol oxidase;Ethylene glycol;Glycolic acid;Glyoxylic acid;Twin-arginine translocation pathway