The radical <i>S</i>-adenosylmethionine-dependent (RS) enzymes are a superfamily of enzymes, which effect a wide range of oxidative modifications of their substrates. They utilize a reduced [4Fe-4S]<sup>+</sup> cluster to reductively generate a canonical 5’-deoxyadenos-5’-yl radical, which then initiates substrate oxidation, often by cleavage of aliphatic C-H bonds. Here we report on two RS enzymes, LipA and MiaB, which catalyze the insertion of sulfur into their substrates. We characterized the reactions by a combination of experimental methods, including Mössbauer spectroscopy and mass spectrometry coupled to liquid chromatography. The results reveal that the auxiliary [4Fe-4S] cluster is partially disassembled during catalysis and provides the sulfur incorporated into the substrate.

New role for an old cofactor

2019 Spring National Meeting

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