Inorganic-Electrochemistry Seminar

Methanotrophic and nitrifying bacteria use copper-dependent membrane monooxygenases to carry out the first steps in their metabolisms: the conversions of methane to methanol by particulate methane monooxygenase (pMMO) and ammonia to hydroxylamine by ammonia monooxygenase (AMO). Due to loss of enzymatic activity upon detergent solubilization from their native intracytoplasmic membranes (ICMs), elucidating the structures and mechanisms of pMMO and AMO has posed significant challenges. Both enzymes consist of three subunits, including PmoB/AmoB, PmoA/AmoA, and PmoC/AmoC. Despite the availability of multiple crystal and cryoelectron microscopy (cryoEM) structures, the location and nature of the copper active site remain controversial. Using cryoEM single particle analysis, we have visualized both pMMO and AMO directly in their native ICMs at high resolution. These in situ structures, combined with spectroscopic and electrochemical data, provide new insight into the function of these environmentally-important membrane-bound cuproenzymes.