flaA-like sequences containing internal termination codons (TAG) in urease-positive thermophilic Campylobacter isolated in Japan

Abstract

Aims: To demonstrate two flaA-like sequences containing two internal termination codons (TAG) in two Japanese strains of urease-positive thermophilic Campylobacter (UPTC).

Methods and results: A primer pair of A1 and A2, which ought to generate a product of approx. 1700 bp of the flaA gene for Campylobacter jejuni, was used to amplify products of approx. 1450 bp for two Japanese strains of UPTC, CF89-12 and CF89-14. After molecular cloning and sequencing, the nucleotide sequences of the amplicons from the two strains were found to be 1461 bp in length and to have nucleotide sequence differences in relation to each other at four nucleotide positions, respectively.

Conclusions: Nucleotide and amino acid sequence alignment and homology analysis demonstrated that the polymerase chain reaction (PCR) amplicons from the two Japanese strains have approx. 83% nucleotide and 80% amino acid sequence homology to the possible open reading frame of the flaA gene of UPTC NCTC 12892.

Significance and impact of the study: Surprisingly, both PCR amplicons from the Japanese UPTC have two internal termination codons (TAG) at nucleotide positions from 775 to 777 and 817 to 819, respectively.