2xji | pdb_00002xji

Structure and Copper-binding Properties of Methanobactins from Methylosinus trichosporium OB3b

spinqualitylabelsall models 2xji, resolution 1.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xji is a 6 chain structure with sequence from Methylosinus trichosporium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CU NonStd Res: BB9, COI Related: 2xjh Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [MBCTN_METTR] 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. Publication Abstract from PubMed Methanobactins (mbs) are a class of copper-binding peptides produced by aerobic methane oxidizing bacteria (methanotrophs) that have been linked to the substantial copper needs of these environmentally important microorganisms. The only characterized mbs are those from Methylosinus trichosporium OB3b and Methylocystis strain SB2. M. trichosporium OB3b produces a second mb (mb-Met), which is missing the C-terminal Met residue from the full-length form (FL-mb). The as-isolated copper-loaded mbs bind Cu(I). The absence of the Met has little influence on the structure of the Cu(I) site, and both molecules mediate switchover from the soluble iron methane mono-oxygenase to the particulate copper-containing enzyme in M. trichosporium OB3b cells. Cu(II) is reduced in the presence of the mbs under our experimental conditions, and the disulfide plays no role in this process. The Cu(I) affinities of these molecules are extremely high with values of (6-7) x 10(20) M(-1) determined at pH >/= 8.0. The affinity for Cu(I) is 1 order of magnitude lower at pH 6.0. The reduction potentials of copper-loaded FL-mb and mb-Met are 640 and 590 mV respectively, highlighting the strong preference for Cu(I) and indicating different Cu(II) affinities for the two forms. Cleavage of the disulfide bridge results in a decrease in the Cu(I) affinity to approximately 9 x 10(18) M(-1) at pH 7.5. The two thiolates can also bind Cu(I), albeit with much lower affinity ( approximately 3 x 10(15) M(-1) at pH 7.5). The high affinity of mbs for Cu(I) is consistent with a physiological role in copper uptake and protection. Copper-Binding Properties and Structures of Methanobactins from Methylosinus trichosporium OB3b.,El Ghazouani A, Basle A, Firbank SJ, Knapp CW, Gray J, Graham DW, Dennison C Inorg Chem. 2011 Jan 21. PMID:21254756 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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