Structures and Protein Engineering of the alpha-Keto Acid C-Methyltransferases SgvM and MrsA for Rational Substrate Transfer.
Sommer-Kamann, C., Breiltgens, J., Zou, Z., Gerhardt, S., Saleem-Batcha, R., Kemper, F., Einsle, O., Andexer, J.N., Muller, M.(2024) Chembiochem 25: e202400258-e202400258
- PubMed: 38887142 
- DOI: https://doi.org/10.1002/cbic.202400258
- Primary Citation of Related Structures:  
8R4Z, 8RPR, 8RVC, 8RVS, 8RWM, 8RWW, 8RXF, 8RXG - PubMed Abstract: 
S?adenosyl-l-methionine-dependent methyltransferases (MTs) are involved in the C-methylation of a variety of natural products. The MTs SgvM from Streptomyces griseoviridis and MrsA from Pseudomonas syringae pv. syringae catalyze the methylation of the ¦Â-carbon atom of ¦Á-keto acids in the biosynthesis of the antibiotic natural products viridogrisein and 3?methylarginine, respectively. MrsA shows high substrate selectivity for 5?guanidino-2-oxovalerate, while other ¦Á-keto acids, such as the SgvM substrates 4-methyl-2-oxovalerate, 2-oxovalerate, and phenylpyruvate, are not accepted. Here we report the crystal structures of SgvM and MrsA in the apo form bound with substrate or S?adenosyl-l-methionine. By investigating key residues for substrate recognition in the active sites of both enzymes and engineering MrsA by site-directed mutagenesis, the substrate range of MrsA was extended to accept ¦Á?keto acid substrates of SgvM with uncharged and lipophilic ¦Â?residues. Our results showcase the transfer of the substrate scope of ¦Á-keto acid MTs from different biosynthetic pathways by rational design.
Organizational Affiliation: 
University of Freiburg, Institute of pharmaceutical science, GERMANY.