Heidi Hu/Sandbox 2: Difference between revisions

The [http://en.wikipedia.org/wiki/Helicobacter_pylori ''H. pylori'']HypA (''Hp''HypA) is a 13.2kDa Ni-chaperone with both a nickel binding site and and structural zinc site.  Zn(II) is coordinated by two CXXCXH motifs in HypA, whereas the Ni(II) is known to bind to the N-terminus with His2 as a known ligand.  The ''Hp''HypA protein has also been characterized as a monomer or a homodimer.  The N-terminal modified monomeric structure has been solved by NMR (PDB ID: [http://www.rcsb.org/pdb/explore/explore.do?structureId=2KDX 2KDX]).  The monomeric structure shows an alpha/beta lobe containing the N- and C-termini well separated from the zinc binding lobe.  The homodimeric ''Hp''HypA has been characterized by NMR to have the similar overall structure with exception to the metal binding sites.  The metal sites in ''Hp''HypA have been characterized by [http://en.wikipedia.org/wiki/X-ray_absorption_spectroscopy ''X-ray absorption spectroscopy''] (XAS) at pH 6.3 and 7.2 similating the internal pH of H. pylori under acid shock or at neutral pH conditions.  Whereas the Ni(II) site is 6-coordinate N/O under both pH conditions, the Zn(II) coordination changes from Cys₄ at neutral pH to Cys₂His₂ at acidic pH with nickel-bound.  Changes in the coordination of structural Zinc site in response to pH has been hypothesized to be linked to altered HypA structures and protein interaction partners.