Identification of (R)-selective ω-aminotransferases by exploring evolutionary sequence space

Several (R)-selective omega-aminotransferases (R-omega ATs) have been reported. The existence of additional R-omega ATs having different sequence characteristics from previous ones is highly expected. In addition, it is generally accepted that R-omega ATs are variants of aminotransferase group III. Based on these backgrounds, sequences in RefSeq database were scored using family profiles of branched-chain amino acid aminotransferase (BCAT) and D-alanine aminotransferase (DAT) to predict and identify putative R-omega ATs. Sequences with two profile analysis scores were plotted on two-dimensional score space. Candidates with relatively similar scores in both BCAT and DAT profiles (i.e., profile analysis score using BCAT profile was similar to profile analysis score using DAT profile) were selected. Experimental results for selected candidates showed that putative R-omega ATs from Saccharopolyspora erythraea (R-omega AT_Sery), Bacillus cellulosilyticus (R-omega ATBcel), and Bacillus thuringiensis (R omega AT_Bthu) had R-omega AT activity. Additional experiments revealed that R-omega AT_Sery also possessed DAT activity while R-omega ATBcel and R-omega AT_Bthu had BCAT activity. Selecting putative R-omega ATs from regions with similar profile analysis scores identified potential R-omega ATs. Therefore, R-omega ATs could be efficiently identified by using simple family profile analysis and exploring evolutionary sequence space.