Fig. 2: EPR spectroscopic characterization and AlphaFold2 predicted structure model of Gms.

a, b Domain organization (a) and the overall architecture of Gms (b) showing an N-terminal domain comprised of six helices, a conserved RS domain, a bridging region with two helices, a β-harpin motif, and a C-terminal SPASM domain. c The interaction between the β-hairpin and the pocket involves two hydrogen bonds between F326 and N351, as well as between S334 and E346. d Cavity map for the active site of Gms reveals the hydrophobic pocket. e Representations of the three [4Fe–4S] clusters in the structure model of Gms. Protein is shown as a cartoon, SAM, and [4Fe–4S] clusters are shown in ball-and-stick models. f X-band CW EPR spectra of various Gms samples (i) the wild-type (WT) Gms reduced by DTH; (ii) subsequently adding SAM to DTH-reduced Gms; (iii) the mutant sample of Gms (C438AC370AC372A) containing only radical SAM (RS) cluster reduced by DTH, and incubated with SAM; (iv) the mutant sample of Gms (C438AC123AC127A) containing only AuxI cluster reduced by DTH; (v) the mutant sample of Gms (C123AC127A C370AC372A) containing only AuxII cluster reduced by DTH. Black, blue and green traces are experimental spectra, and the red traces are simulated spectra.