Crystallization and X-ray diffraction properties of Baeyer-Villiger monooxygenase MtmOIV from the mithramycin biosynthetic pathway in Streptomyces argillaceus

The Baeyer–Villiger monooxygenase MtmOIV from Streptomyces argillaceus is a 56 kDa FAD‐dependent and NADPH‐dependent enzyme that is responsible for the key frame‐modifying step in the biosynthesis of the natural product mithramycin. Crystals of MtmOIV were flash‐cooled and diffracted to 2.69 Å resolution using synchrotron radiation on beamline SER‐CAT 22‐ID at the Advanced Photon Source. Crystals of MtmOIV are monoclinic and light‐scattering data reveal that the enzyme forms dimers in solution. The rotation function suggests the presence of two dimers in the asymmetric unit. l‐­Selenomethionine‐incorporated MtmOIV has been obtained. Structural solution combining molecular‐replacement phases and anomalous phases from selenium is in progress.