Recombinant Methylosinus trichosporium Methanobactin mb-OB3b (mbnA)

Function

Chalkophore involved in scavenging, uptake and suppression of toxicity of copper. Each apo-methanobactin (apo-mb) complexes 1 Cu(2+) or Cu(1+) ion to form Cu(1+)-mb (Cu-mb) which is then taken up by the cell. Enhances growth rate in the presence of copper and reduces growth lag upon exposition to elevated levels of copper. Cu-mb contributes to the switchover from soluble methane monooxygenase (sMMO) to the membrane-bound particulate MMO (pMMO) by inducing transcription of pMMO subunit A. It also stimulates the enzymatic activity of pMMO. In the absence of copper, binds other metal ions, like Zn(2+), Ag(1+), Au(3+), Co(2+), Cd(2+), Fe(3+), Hg(2+), Mn(2+), Ni(2+), Pb(2+) or U(6+), but not Ba(2+), Ca(2+), La(2+), Mg(2+) or Sr(2+). Uptake is an active process, which may involve TonB-dependent transporters, and as such does not involve porins. Cu-Mb can be taken up by other methanotrophic bacteria but not by E.coli. Has Cu-dependent superoxide dismutase-like activity. Shows reductant-dependent oxidase and hydrogen peroxide reductase activities. Reduces copper-levels in liver in a rat model of Wilson disease

Subcellular Location

Secreted; Cytoplasm

Subunit

Monomer. In the absence of copper, may exist as a dimer or an oligomer

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• Kim H.J. et al. Purification and physical-chemical properties of methanobactin: a chalkophore from Methylosinus trichosporium OB3b. — Biochemistry (2005)
• Hakemian A.S. et al. The copper chelator methanobactin from Methylosinus trichosporium OB3b binds copper(I). — J. Am. Chem. Soc. (2005)
• Choi D.W. et al. Effect of methanobactin on the activity and electron paramagnetic resonance spectra of the membrane-associated methane monooxygenase in Methylococcus capsulatus Bath. — Microbiology (2005)
• Choi D.W. et al. Spectral, kinetic, and thermodynamic properties of Cu(I) and Cu(II) binding by methanobactin from Methylosinus trichosporium OB3b. — Biochemistry (2006)
• Choi D.W. et al. Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b. — J. Inorg. Biochem. (2006)