%0 Journal Article
%T Electron transport in acetate-grown Methanosarcina acetivorans
%A Mingyu Wang
%A Jean-Francois Tomb
%A James G Ferry
%J BMC Microbiology
%D 2011
%I BioMed Central
%R 10.1186/1471-2180-11-165
%X A component of the CO dehydrogenase/acetyl-CoA synthase (CdhAE) was partially purified and shown to reduce a ferredoxin purified using an assay coupling reduction of the ferredoxin to oxidation of CdhAE. Mass spectrometry analysis of the ferredoxin identified the encoding gene among annotations for nine ferredoxins encoded in the genome. Reduction of purified membranes from acetate-grown cells with ferredoxin lead to reduction of membrane-associated multi-heme cytochrome c that was re-oxidized by the addition of either the heterodisulfide of coenzyme M and coenzyme B (CoM-S-S-CoB) or 2-hydoxyphenazine, the soluble analog of methanophenazine (MP). Reduced 2-hydoxyphenazine was re-oxidized by membranes that was dependent on addition of CoM-S-S-CoB. A genomic analysis of Methanosarcina thermophila, a non-H2-utilizing acetotrophic methanogen, identified genes homologous to cytochrome c and the Ma-Rnf complex of M. acetivorans.The results support roles for ferredoxin, cytochrome c and MP in the energy-conserving electron transport pathway of non-H2-utilizing acetotrophic methanogens. This is the first report of involvement of a cytochrome c in acetotrophic methanogenesis. The results suggest that diverse acetotrophic Methanosarcina species have evolved diverse membrane-bound electron transport pathways leading from ferredoxin and culminating with MP donating electrons to the heterodisulfide reductase (HdrDE) for reduction of CoM-S-S-CoB.The decomposition of complex organic matter to methane (biomethanation) in diverse anaerobic habitats of Earth's biosphere involves an anaerobic microbial food chain comprised of distinct metabolic groups, the first of which metabolizes the complex organic matter primarily to acetate and also formate or H2 that are growth substrates for two distinct methane-producing groups (methanogens) [1]. The methyl group of acetate contributes most of the methane produced in the biomethanation process via the aceticlastic pathway whereas the remainde
%U http://www.biomedcentral.com/1471-2180/11/165