2ca9: Difference between revisions

The survival of Helicobacter pylori in the human stomach critically relies, on the availability and use of nickel, an absolute cofactor of the, important virulence determinant urease. Nickel-responsive gene regulation, is mediated by HpNikR, a protein belonging to the ribbon-helix-helix, family of transcriptional regulators. Unlike its homologues, HpNikR acts, as both a repressor and an activator within an acid adaptation cascade. We, report the crystal structure of the full-length HpNikR in a nickel-free, conformation and two nickel-bound structures obtained in different, conditions: Ni1-HpNikR and Ni2-HpNikR. Apo-HpNikR shows the same global, fold as its bacterial homologues although with an unusual closed, trans-conformation and asymmetrical quaternary arrangement. The structure, of Ni1-HpNikR in the presence of nickel has two different sides, one, showing nickel binding similar to that of known NikRs and the other, reflecting an intermediate state. The structure of Ni2-HpNikR obtained, using a shorter exposure to nickel provides another snapshot of the nickel, incorporation. Altogether, the three structures have allowed us to, determine the route for nickel within HpNikR and reveal the cooperativity, between the tetramerization domain and the DNA-binding domain. Experiments, using point mutations of HpnikR residues involved in nickel, internalisation confirm that these residues are critical for HpNikR, functions in vivo.

2CA9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Helicobacter_pylori Helicobacter pylori] with FMT and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CA9 OCA].  

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