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.