Catalytic machinery of methane oxidation in particulate methane monooxygenase (pMMO)

ABSTR A C T In this focused review, we portray the recently reported 2.5 angstrom cyro-EM structure of the particulate methane monooxygenase (pMMO) from M. capsulatus (Bath). The structure of the functional holo-pMMO near atomic resolution has uncovered the sites of the copper cofactors including the location of the active site in the enzyme. The three coppers seen in the original X-ray crystal structures of the enzyme are now augmented by additional coppers in the transmembrane domain as well as in the water-exposed C-terminal subdomain of the PmoB subunit. The cryo-EM structure offers the first glimpse of the catalytic machinery capable of methane oxidation with high selectivity and efficiency. The findings are entirely consistent with the biochemical and biophysical findings previously reported in the literature, including the chemistry of hydrocarbon hydroxylation, regener-ation of the catalyst for multiple turnovers, and the mechanism of aborting non-productive cycles to ensure kinetic competence.

Automated summary

This focused review describes the 2.5 angstrom cyro-EM structure of particulate methane monooxygenase (pMMO), revealing the locations of copper cofactors and active sites, providing insights into the catalytic machinery capable of methane oxidation with high selectivity and efficiency.