ISSN:
1523-5378
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Background. The gastric pathogen Helicobacter pylori produces urease in amounts up to 10% of its cell protein. This enzyme, which catalyzes the hydrolysis of urea to ammonia and carbon dioxide, protects the bacterium from gastric acid. Urease, a nickel metalloenzyme, requires active uptake of nickel ions from the environment to maintain its activity. NixA is a nickel transport protein that resides in the cytoplasmic membrane. Mutation of nixA significantly reduces but does not abolish urease activity, strongly suggesting the presence of a second transporter. We postulated that the dipeptide permease (dpp) genes that are homologous to the nik operon of Escherichia coli could be a second nickel transporter. The predicted Dpp polypeptides DppA, DppC, and DppD of H. pylori share approximately 40%, 53%, and 56% amino acid sequence identity with their respective E. coli homologs.Methods. A mutation in dppA, constructed by insertional inactivation with a chloramphenicol resistance cassette, was introduced by allelic exchange into H. pylori strain 26695.Results. When compared to the parental strain, urease activity was not decreased in a dppA mutant.Conclusions. DppA does not contribute to the synthesis of catalytically active urease in H. pylori 26695 and is likely not a nickel importer in H. pylori
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1523-5378.2005.00348.x
