Characterization of a novel cytochrome cGJ as the electron acceptor of XoxF-MDH in the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV

Publication date: Available online 4 April 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Wouter Versantvoort, Arjan Pol, Lena J. Daumann, James A. Larrabee, Aidan H. Strayer, Mike S.M. Jetten, Laura van Niftrik, Joachim Reimann, Huub J.M. Op den CampAbstractMethanotrophs play a prominent role in the global carbon cycle, by oxidizing the potent greenhouse gas methane to CO2. Methane is first converted into methanol by methane monooxygenase. This methanol is subsequently oxidized by either a calcium-dependent MxaF-type or a lanthanide-dependent XoxF-type methanol dehydrogenase (MDH). Electrons from methanol oxidation are shuttled to a cytochrome redox partner, termed cytochrome cL. Here, the cytochrome cL homolog from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV was characterized. SolV cytochrome cGJ is a fusion of a XoxG cytochrome and a periplasmic binding protein XoxJ. Here we show that XoxGJ functions as the direct electron acceptor of its corresponding XoxF-type MDH and can sustain methanol turnover, when a secondary cytochrome is present as final electron acceptor. SolV cytochrome cGJ (XoxGJ) further displays a unique, red-shifted absorbance spectrum, with a Soret and Q bands at 440, 553 and 595 nm in the reduced state, respectively. VTVH-MCD spectroscopy revealed the presence of a low spin iron heme and the data further shows that the heme group exhibits minimal ruffling. The midpoint potential Em,pH7 of +...

Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - April 5, 2019 Category: Biochemistry Source Type: research