In this study, we tried to characterize Streptomyces peucetius CYP157C4 with homology modeling using three cytochrome P450 (CYP) structures (CYP157C1, CYP164A2, and CYP107L1), having discovered that CYP157C4 lacks the ExxR motif that was considered invariant in all CYPs. We used Discovery Studio 3.5 to build our model after first assessing the stereochemical quality and side-chain environment, and a 7-ethoxycoumarin substrate was docked into the final model. The model-substrate complex allowed us to identify functionally important residues and validate the active-site architecture. We found a distance of 4.56 Å between the 7-ethoxycoumarin and the active site of the heme, and cloning and an in vitro assay of the CYP157C4 showed the dealkylation of the substrate. Since the details regarding this group of CYP structures are still unknown, the findings of this study may provide elucidation to assist with future efforts to find a legitimate substrate.
Keywords: 7-ethoxycoumarin; Cytochrome P450; Homology modelling; Streptomyces peucetius; in vitro assay.