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Methanobactin and the Link between Copper and Bacterial Methane Oxidation

Lookup NU author(s): Professor Christopher Dennison


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Methanobactins (mbs) are low-molecular-mass (< 1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu2+ to Cu1+. In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs.

Publication metadata

Author(s): DiSpirito AA, Semrau JD, Murrell JC, Gallagher WH, Dennison C, Vuilleumier S

Publication type: Review

Publication status: Published

Journal: Microbiology and Molecular Biology Reviews

Year: 2016

Volume: 80

Issue: 2

Pages: 387-409

Print publication date: 01/06/2016

Online publication date: 16/03/2016

Acceptance date: 01/01/1900

ISSN (print): 1092-2172

ISSN (electronic): 1098-5557



DOI: 10.1128/MMBR.00058-15