Premium
Characterization and Mechanistic Study of the Radical SAM Enzyme ArsS Involved in Arsenosugar Biosynthesis
Author(s) -
Cheng Jinduo,
Ji Wenjuan,
Ma Suze,
Ji Xinjian,
Deng Zixin,
Ding Wei,
Zhang Qi
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202015177
Subject(s) - biosynthesis , biochemistry , enzyme , chemistry , cyanobacteria , atp synthase , algae , stereochemistry , biology , bacteria , ecology , genetics
Arsenosugars are a group of arsenic‐containing ribosides that are found predominantly in marine algae but also in terrestrial organisms. It has been proposed that arsenosugar biosynthesis involves a key intermediate 5′‐deoxy‐5′‐dimethylarsinoyl‐adenosine (DDMAA), but how DDMAA is produced remains elusive. Now, we report characterization of ArsS as a DDMAA synthase, which catalyzes a radical S‐adenosylmethionine (SAM)‐mediated alkylation (adenosylation) of dimethylarsenite (DMAs III ) to produce DDMAA. This radical‐mediated reaction is redox neutral, and multiple turnover can be achieved without external reductant. Phylogenomic and biochemical analyses revealed that DDMAA synthases are widespread in distinct bacterial phyla with similar catalytic efficiencies; these enzymes likely originated from cyanobacteria. This study reveals a key step in arsenosugar biosynthesis and also a new paradigm in radical SAM chemistry, highlighting the catalytic diversity of this superfamily of enzymes.