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Methanobactin and MmoD work in concert to act as the ‘copper‐switch’ in methanotrophs
Author(s) -
Semrau Jeremy D.,
Jagadevan Sheeja,
DiSpirito Alan A.,
Khalifa Ashraf,
Scanlan Julie,
Bergman Brandt H.,
Freemeier Brittani C.,
Baral Bipin S.,
Bandow Nathan L.,
Vorobev Alexey,
Haft Daniel H.,
Vuilleumier Stéphane,
Murrell J. Colin
Publication year - 2013
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12150
Subject(s) - methane monooxygenase , operon , gene , biology , bacteria , biochemistry , gene expression , copper , methanotroph , enzyme , anaerobic oxidation of methane , microbiology and biotechnology , chemistry , genetics , escherichia coli , catalysis , organic chemistry
Summary Biological oxidation of methane to methanol by aerobic bacteria is catalysed by two different enzymes, the cytoplasmic or soluble methane monooxygenase ( sMMO ) and the membrane‐bound or particulate methane monooxygenase ( pMMO ). Expression of MMOs is controlled by a ‘copper‐switch’, i.e. sMMO is only expressed at very low copper : biomass ratios, while pMMO expression increases as this ratio increases. Methanotrophs synthesize a chalkophore, methanobactin, for the binding and import of copper. Previous work suggested that methanobactin was formed from a polypeptide precursor. Here we report that deletion of the gene suspected to encode for this precursor, mbnA , in M ethylosinus trichosporium OB3 b, abolishes methanobactin production. Further, gene expression assays indicate that methanobactin, together with another polypeptide of previously unknown function, MmoD , play key roles in regulating expression of MMOs . Based on these data, we propose a general model explaining how expression of the MMO operons is regulated by copper, methanobactin and MmoD . The basis of the ‘copper‐switch’ is MmoD , and methanobactin amplifies the magnitude of the switch. Bioinformatic analysis of bacterial genomes indicates that the production of methanobactin‐like compounds is not confined to methanotrophs, suggesting that its use as a metal‐binding agent and/or role in gene regulation may be widespread in nature.