biostudies-literatureJeyachandran VRHoward Hughes Medical InstituteNational Institutes of HealthNIGMS NIH HHSNational Science Foundation102153https://www.ebi.ac.uk/biostudies/studies/S-EPMC10197145biostudies-literatureUnknown68Radical S-adenosylmethionine (SAM) enzymes use a common catalytic core for diverse transformations. While all radical SAM enzymes bind a Fe₄S₄ cluster via a characteristic tri-cysteine motif, many bind additional metal cofactors. Recently reported structures of radical SAM enzymes that use methylcobalamin or additional iron-sulfur clusters as cosubstrates show that these auxiliary units are anchored by N- and C-terminal domains that vary significantly in size and topology. Despite this architectural diversity, all use a common surface for auxiliary cofactor docking. In the sulfur insertion and metallocofactor assembly systems evaluated here, interaction with iron-sulfur cluster assembly proteins or downstream scaffold proteins is an important component of catalysis. SCurrent opinion in chemical biologyStructural insights into auxiliary cofactor usage by radical S-adenosylmethionine enzymes.PMC10197145R35 GM119707GM119707MCB -1158486Jeyachandran VRBoal AKfalseStructural insights into auxiliary cofactor usage by radical S-adenosylmethionine enzymes.Radical S-adenosylmethionine (SAM) enzymes use a common catalytic core for diverse transformations. While all radical SAM enzymes bind a Fe₄S₄ cluster via a characteristic tri-cysteine motif, many bind additional metal cofactors. Recently reported structures of radical SAM enzymes that use methylcobalamin or additional iron-sulfur clusters as cosubstrates show that these auxiliary units are anchored by N- and C-terminal domains that vary significantly in size and topology. Despite this architectural diversity, all use a common surface for auxiliary cofactor docking. In the sulfur insertion and metallocofactor assembly systems evaluated here, interaction with iron-sulfur cluster assembly proteins or downstream scaffold proteins is an important component of catalysis. S2022-01-01T00:00:00Z2022 Jun2025-04-21T23:46:22.145Z2025-04-05T19:15:10.015ZS-EPMC101971453551246510.1016/j.cbpa.2022.102153