Genetic heterogeneity of urease gene loci in urease-positive thermophilic Campylobacter (UPTC)

Abstract

Degenerate PCR primers in silico based on the two urease structural genes, ureA and ureB, were designed for urease-positive thermophilic Campylobacter (UPTC). Resultant PCR amplification employing these primers generated an amplicon of approximately 2kb, which was cloned and sequenced in UPTC (n=12) isolated from various parts of Europe and Japan. Overall, sequence similarities were shown to be 96.7 to 99.9%. Following sequence alignment analysis, the approximate 1.96kb regions were deduced to consist of parts of ureA (about 570bps) and ureB (about 1390bps) with an overlapping region between the ureA and ureB gene loci. Although a total of 144 heterogeneous sites of all substitutions were located throughout this region, the substitution ratio was higher in the ureA region (1/Omega10bases) than in the ureB region (1/Omega15bases). A resulting dendrogram was constructed, which was based on the nucleotide sequence data of 12 UPTC isolates and demonstrated that the UPTC were genetically variable. They formed a major cluster with Helicobacter, separate from the other urease-producing bacteria examined, suggesting a shared ancestry between UPTC and Helicobacter.