Component of the wyosine derivatives biosynthesis pathway that catalyzes the condensation of N-methylguanine with 2 carbon atoms from pyruvate to form the tricyclic 4-demethylwyosine (imG-14) on guanosine-37 of tRNA(Phe). N(1)-methylguanosine(37) in tRNA(Phe) + pyruvate + S-adenosyl-L-methionine = 4-demethylwyosine(37) in tRNA(Phe) + 5'-deoxyadenosine + CO2 + H2O + L-methionine Binds 1 [2Fe-2S] cluster. Binds 1 [4Fe-4S] cluster. The [4Fe-4S] cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine. Monomer. Belongs to the TYW1 family.