Required for methylation of hopanoids at the C-2 position. Binds 1 [4Fe-4S] cluster. The cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine. Up-regulated in an EcfG-dependent manner under a variety of stresses, including high-temperature, acidic, alkaline and hyperosmotic conditions. Deletion mutant does not produce C-2 methylated triterpenoids. Belongs to the radical SAM superfamily.