Methanobactin and the Link between Copper and Bacterial Methane Oxidation.

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.

Isolation of methanobactin from the spent media of methane-oxidizing bacteria.

Chalkophores are low molecular mass modified peptides involved in copper acquisition in methane-oxidizing bacteria (MOB). A screening method for the detection of this copper-binding molecule is presented in Chapter 16. Here we describe methods to (1) maximize expression and secretion of chalkophores, (2) concentrate chalkophores from the spent media of MOB, and (3) purify chalkophores.

A comparison of methanobactins from Methylosinus trichosporium OB3b and Methylocystis strain Sb2 predicts methanobactins are synthesized from diverse peptide precursors modified to create a common core for binding and reducing copper ions.

Methanobactins (mb) are low-molecular mass, copper-binding molecules secreted by most methanotrophic bacteria. These molecules have been identified for a number of methanotrophs, but only the one produced by Methylosinus trichosporium OB3b (mb-OB3b) has to date been chemically characterized. Here we report the chemical characterization and copper binding properties of a second methanobactin, which is produced by Methylocystis strain SB2 (mb-SB2).

NMR, mass spectrometry and chemical evidence reveal a different chemical structure for methanobactin that contains oxazolone rings.

Methanobactin (mb) is a small copper-binding peptide produced by methanotrophic bacteria and is intimately involved in both their copper metabolism and their role in the global carbon cycle. The structure for methanobactin comprises seven amino acids plus two chromophoric residues that appear unique to methanobactin. In a previously published structure, both chromophoric residues contain a thiocarbonyl attached to a hydroxyimidazolate ring.