title: Cloning, expression, and characterization of a Coxiella burnetii Cu/Zn Superoxide dismutase.
abstract: BACKGROUND
  Periplasmically localized copper-zinc co-factored superoxide dismutase (SodC) enzymes have been identified in a wide range of Gram-negative bacteria and are proposed to protect bacteria from exogenously produced toxic oxygen radicals, which indicates the potential significance of a Coxiella burnetii SodC.
  
  
  RESULTS
  Assays for SOD activity demonstrated that the cloned C. burnetii insert codes for a SOD that was active over a wide range of pH and inhibitable with 5 mM H2O2 and 1 mM sodium diethyldithiocarbamate, a characteristic of Cu/ZnSODs that distinguishes them from Fe or Mn SODs. The sodC was expressed by C. burnetii, has a molecular weight of approximately 18 kDa, which is consistent with the predicted molecular weight, and localized towards the periphery of C. burnetii. Over expression of the C. burnetii sodC in an E. coli sodC mutant restored resistance to H2O2 killing to wild type levels.
  
  
  CONCLUSIONS
  We have demonstrated that C. burnetii does express a Cu/ZnSOD that is functional at low pH, appears to be excreted, and was able to restore H2O2 resistance in an E. coli sodC mutant. Taken together, these results indicate that the C. burnetii Cu/ZnSOD is a potentially important virulence factor.
authors.affiliation: Department of Biology, University of Central Oklahoma, 100 North University Drive, Edmond, OK, USA. rbrennan1@uco.edu.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Brennan
authors.affiliation: American Type Culture Collection, Manassas, VA, USA. kkiss@atcc.org.
authors.forename: Katalin
authors.initials: K
authors.lastname: Kiss
authors.affiliation: Department of Biology, University of Central Oklahoma, 100 North University Drive, Edmond, OK, USA. rbaalman@uco.edu.
authors.forename: Rachael
authors.initials: R
authors.lastname: Baalman
authors.affiliation: Department of Medical Microbiology and Immunology, Texas A & M University System Health Science Center, College Station, TX, USA. jsamuel@medicine.tamhsc.edu.
authors.forename: James E
authors.initials: JE
authors.lastname: Samuel
mesh_terms: D003001:Cloning, Molecular; D016997:Coxiella burnetii / Q000201:enzymology* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000032:analysis; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase