Molecular analysis of urease genes from a newly identified uncultured species of Helicobacter

Abstract

"Gastrospirillum hominis" is an uncultured gastric spiral bacterium that has recently been shown by 16S rDNA sequence analysis to be a newly recognized species of Helicobacter that infects humans, and it has been provisionally designated "Helicobacter heilmannii." We used PCR to directly amplify the urease structural genes of "H. heilmannii" from infected gastric tissue. DNA sequence analysis identified two open reading frames, ureA and ureB, which code for polypeptides with predicted molecular weights of 25,729 and 61,831, respectively. The urease subunit genes from "H. heilmannii" were cloned and expressed in Escherichia coli. Western blot (immunoblot) analysis showed that antiserum directed against the ureA and ureB gene products from H. pylori was cross-reactive with the corresponding polypeptides from "H. heilmannii." Analysis of the derived amino acid sequences of "H. heilmannii" UreA and UreB demonstrated that "H. heilmannii" urease is more highly related to the urease from H. felis (found in the stomachs of cats and dogs) than to the urease from H. pylori. These data are consistent with 16S rDNA sequence analysis and suggest that "H. heilmannii" is phylogenetically most closely related to H. felis.

The Helicobacter pylori UreI Protein Is Not Involved in Urease Activity but Is Essential for Bacterial Survival In Vivo

“…3). PCR experiments have suggested that there is a ureI gene in Helicobacter heilmannii (22) and in Helicobacter mustelae (unpublished data).…”

Characterization of Multiple Helicobacter bizzozeronii Isolates From a Finnish Patient With Severe Dyspeptic Symptoms and Chronic Active Gastritis

“…Antiserum directed against the ureA and ureB gene products from H. pylori has been demonstrated to be cross-reactive with the corresponding polypeptides from ''H. heilmannii'' [8].…”

“…heilmannii'' derived from clones from two different patients revealed that this group of organisms comprises at least two separate taxa designated as ''H. heilmannii'' types one and two [8,13,14]. Further studies [13] showed that ''H.…”

Presence of Multiple “ Helicobacter heilmannii ” Strains in an Individual Suffering from Ulcers and in His Two Cats

“…Amplification of a ureB 580-bp DNA fragment. The forward primer (5Ј-GGG CGATAAAGTGCGCTTG-3Ј [19-mer]) and the reverse primer (5Ј-CTGGTC AATGAGAGCAGG-3Ј [18-mer]) were derived from the published "H. heilmannii" urease B sequence EMBL L25079 (29) and used to amplify a 580-bp segment of "H. heilmannii" urease B subunit gene as already described (24). The amplification reaction consisted of 1-to 2-l DNA samples in a final volume of 50 l containing 1ϫ PCR buffer (Pharmacia Biotech, Dübendorf, Switzerland), 200 M (each) deoxynucleoside triphosphate (Pharmacia), 100 pmol of primers (Microsynth GmbH, Balgach, Switzerland), and 2.5 U of Taq DNA polymerase (Pharmacia).…”