Old yellow enzyme (OYE) YqjM-like FMN binding domain. YqjM is involved in the oxidative stress response of Bacillus subtilis. Like the other OYE members, each monomer of YqjM contains FMN as a non-covalently bound cofactor and uses NADPH as a reducing agent. The YqjM enzyme exists as a homotetramer that is assembled as a dimer of catalytically dependent dimers, while other OYE members exist only as monomers or dimers. Moreover, the protein displays a shared active site architecture where an arginine finger at the COOH terminus of one monomer extends into the active site of the adjacent monomer and is directly involved in substrate recognition. Another remarkable difference in the binding of the ligand in YqjM is represented by the contribution of the NH2-terminal tyrosine instead of a COOH-terminal tyrosine in OYE and its homologs.
Comment:Note that in 1Z48, an arginine finger (R336) at the COOH terminus of one monomer extends into the active site of the adjacent monomer and is involved in substrate recognition
Comment:Substrate binding site based on 3 substrates: sulfate, pHBA, and pNP
Jiyao W et al.(2023). "The conserved domain database in 2023.",