The organisation of methanol dehydrogenase and c-type cytochromes on the respiratory membrane of Methylophilus methylotrophus

AbstractThe membrane-impermeant, protein-labelling reagent [14C]isethionyl acetimidate has been used to investigate the detailed topography of the membrane-associated methanol oxidase system in the methylotrophic bacterium Methylophilus methylotrophus. The results show that methanol dehydrogenase and cytochrome c1 are significantly less exposed on the periplasmic surface of the membrane than either cytochrome CH or an as yet unidentified 12-kDa protein. The partial crypticity of the methanol dehydrogenase has been confirmed by fingerprinting with V8 protease. The results are discussed in terms of the electron transfer functions of the various redox proteins