Dipeptide synthesis by L-amino acid ligase from Ralstonia solanacearum

Despite its utility, dipeptides have not been widely used due to the absence of an efficient manufacturing method. Recently, a novel method for effective production of dipeptides using l-amino acid α-ligase (Lal) is presented. Lal, which is only identified in Bacillus subtilis, catalyzes dipeptide synthesis from unprotected amino acids in an ATP-dependent manner. However, not all the dipeptide can be synthesized by Lal from B. subtilis (BsLal) due to its substrate specificity. Here, we attempted to find a novel Lal exhibiting different substrate specificity from BsLal. By in silico screening based on the amino acid sequence of BsLal, RSp1486a an unknown protein from Ralstonia solanacearum was found to show the Lal activity. RSp1486a exhibited different substrate specificity from BsLal, and preferably synthesized hetero-dipeptides where more bulky amino acid was placed at N terminus and less bulky amino acid was placed at C terminus in opposition to those synthesized by BsLal.