Design and Synthesis of SAM Analogues for Labeling Substrates of ACP Transferases.

S-Adenosylmethionine (SAM) is an important cofactor in a variety of biochemical reactions. In addition to serving as a versatile methyl donor, the 3-amino-3-carboxypropyl (ACP) group of SAM is also involved in the biosynthesis of many important natural products including antibiotics and signaling molecules. We developed four SAM-based probes for labeling the substrates of the ACP transferases. SAM3 successfully labels the substrate of BjaI in the biosynthesis of isovaleryl homoserine lactone (IV-AHL), a quorum-sensing signaling molecule. SAM1 is capable of labeling the substrate of CntL in staphylopine biosynthesis with both pure compounds and complex metabolites. Therefore, they are promising tools for labeling and identifying the substrates of ACP transferases.