Catalyzes activation of the choline trimethylamine-lyase CutC under anaerobic conditions by generation of an organic free radical on a glycine residue, via a homolytic cleavage of S-adenosyl-L-methionine (SAM). Is involved in the anaerobic choline utilization pathway that allows D.alaskensis to grow on choline as a source of carbon and energy. glycyl-[protein] + reduced [flavodoxin] + S-adenosyl-L-methionine = 5'-deoxyadenosine + glycin-2-yl radical-[protein] + H(+) + L-methionine + semiquinone [flavodoxin] Binds 2 [4Fe-4S] clusters (PubMed:24854437). One cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine (Probable). Amine and polyamine metabolism; choline degradation. Monomer. Belongs to the organic radical-activating enzymes family.