Research Abstract:
We are interested in how cells control intracellular levels of essential trace metals. A balance must be achieved between levels that are sufficient for growth and those that are toxic to the cell. Our research focuses on the regulation and intracellular trafficking of nickel in microbes, in particular Escherichia coli and Helicobacter pylori. In these bacteria, nickel-enzymes are synthesized with the help of specific nickel-binding chaperones. The nickel-dependent transcriptional regulator NikR binds free nickel ions and represses expression of nickel uptake genes. NikR has also been shown to postively regulate gene expression of at least one operon (urrease) in H. pylori. The function of NikR indicates that free nickel ions accumulate only after sufficient nickel has been acquired to synthesize nickel-dependent enzymes. However, the high-affinity of NikR for nickel ions suggest that nickel-trafficking pathways must actively compete with NikR for newly acquired nickel ions. We are currently studying the mechanism by which this partitioning is achieved. Our approach combines biochemical and biophysical studies of purified proteins (for example, fluorescence and UV-visible spectroscopy) with in vivo studies of protein function (molecular genetics, reporter assays) to correlate molecular properties, such as ligand-binding affinity, with biological function.
Selected Publications:
Iwig JS and Chivers PT. DNA recognition and wrapping by E. coli RcnR. J. Mol. Biol. 2009 293:514-526.
Benanti EL and Chivers PT. An intact urease assembly pathway is required to compete with NikR for nickel ions in Helicobacter pylori. J. Bacteriol. 2009 189:2405-2408 .
Iwig JS, Leitch S, Herbst RW, Maroney MJ, Chivers PT. Ni(II) and Co(II) sensing by Escherichia coli RcnR. J. Am. Chem. Soc. 2008 130: 7592-7606.
Bradley MJ, Chivers PT and Baker N. A Molecular dynamics simulation of the Escherichia coli NikR protein: equilibrium conformational fluctuations reveal interdomain allosteric communication pathways. J. Mol. Biol. 2008 378: 1155-73.
Benanti EL and Chivers PT. The N-terminal arm of the Helicobacter pylori Ni2+-dependent Transcription Factor NikR is Required for Specific DNA binding J. Biol. Chem. 2007 282: 20365-75.
Last Updated: 10/22/2009 |