{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,12]],"date-time":"2026-04-12T19:22:57Z","timestamp":1776021777757,"version":"3.50.1"},"reference-count":24,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2005,9,16]],"date-time":"2005-09-16T00:00:00Z","timestamp":1126828800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Helicobacter"],"published-print":{"date-parts":[[2005,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:p><jats:bold>Background.\u2002<\/jats:bold> The gastric pathogen <jats:italic>Helicobacter pylori<\/jats:italic> 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 <jats:italic>nixA<\/jats:italic> significantly reduces but does not abolish urease activity, strongly suggesting the presence of a second transporter. We postulated that the dipeptide permease (<jats:italic>dpp<\/jats:italic>) genes that are homologous to the <jats:italic>nik<\/jats:italic> operon of <jats:italic>Escherichia\u00a0coli<\/jats:italic> could be a second nickel transporter<jats:italic>.<\/jats:italic> The predicted Dpp polypeptides DppA, DppC, and DppD of <jats:italic>H.\u00a0pylori<\/jats:italic> share approximately 40%, 53%, and 56% amino acid sequence identity with their respective <jats:italic>E.\u00a0coli<\/jats:italic> homologs.<\/jats:p><jats:p><jats:bold>Methods.\u2002<\/jats:bold> A mutation in <jats:italic>dppA<\/jats:italic>, constructed by insertional inactivation with a chloramphenicol resistance cassette, was introduced by allelic exchange into <jats:italic>H. pylori<\/jats:italic> strain 26695.<\/jats:p><jats:p><jats:bold>Results.\u2002<\/jats:bold> When compared to the parental strain, urease activity was not decreased in a <jats:italic>dppA<\/jats:italic> mutant.<\/jats:p><jats:p><jats:bold>Conclusions.\u2002<\/jats:bold> DppA does not contribute to the synthesis of catalytically active urease in <jats:italic>H.\u00a0pylori<\/jats:italic> 26695 and is likely not a nickel importer in <jats:italic>H.\u00a0pylori<\/jats:italic><\/jats:p>","DOI":"10.1111\/j.1523-5378.2005.00348.x","type":"journal-article","created":{"date-parts":[[2005,9,16]],"date-time":"2005-09-16T15:53:52Z","timestamp":1126886032000},"page":"416-423","source":"Crossref","is-referenced-by-count":20,"title":["Contribution of <i>dppA<\/i> to Urease Activity in <i>Helicobacter pylori<\/i> 26695"],"prefix":"10.1111","volume":"10","author":[{"given":"Gregg S.","family":"Davis","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Harry 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