5). p value < 0.05 was considered significant. Nucleotide sequence accession number The nucleotide sequence data of ure gene complex and the yut gene reported in this paper have been deposited in GenBank database under accession numbers DQ350880 and EU527335 respectively. Results Characterization of urease genes Primers

U1 and U2 were designed to amplify the ure structural (ureA, ureB, ureC) genes of Y. enterocolitica. Although amplification was obtained with biovar 1B, 2 and 4 strains, these primers did not consistently amplify the ure structural genes of biovar 1A strains. Thus, new primers were designed to amplify each of the ure structural and accessory (ureE, ureF, ureG, ureD) genes separately, and selleck the intergenic regions so as to encompass the entire urease gene cluster of biovar 1A strain. selleck compound Amplicons of expected sizes were obtained for all genes except ureB and the intergenic regions namely ureA-ureB, ureB-ureC and ureC-ureE (Table 1). The sequences thus obtained were analyzed for homology with sequences available in databases, edited and combined to obtain 7,180 bp sequence of ure gene cluster of biovar 1A selleck screening library strain (See Additional file 1 for ure gene cluster sequence). Seven

ORFs were identified in the ure gene cluster of Y. enterocolitica biovar 1A strain and designated as ureA, ureB, ureC, ureE, ureF, ureG and ureD (Fig. 1) as in the ure gene complex of Y. enterocolitica 8081 (biovar 1B, accession number AM286415). As with Y. enterocolitica 8081, yut gene which encodes a urea transport protein was present downstream Adenosine triphosphate of the ure

gene cluster. All ORFs had ATG as the start codon except ureG where the start codon was GTG. These ORFs were preceded by ribosome-binding consensus sequence. Although ure gene cluster of biovar 1A strain was broadly similar to that of biovar 1B and biovar 4 strains, differences were identified. These were – smaller ureB gene and ureA-ureB intergenic region and larger ureB-ureC and ureC-ureE intergenic regions in biovar 1A strain (Table 2). The size of ureB gene of Y. enterocolitica biovar 1A was identical to ureB of Y. aldovae, Y. bercovieri, Y. intermedia, Y. mollaretii and exhibited higher nucleotide sequence identity to these species than to Y. enterocolitica biovar 1B or 4. The stop codon of ureG overlapped with the start codon of ureD gene. The G + C content of the urease gene cluster was 49.76% which was typical of Y. enterocolitica with G + C content of 47.27%. Table 2 Urease structural and accessory genes and the intergenic regions thereof, in Y. enterocolitica biovar 1A.