장염비브리오가 보유하는 ß-Lactamase (VPA0477)의 유전학적 특성

Using 108 strains of Vibrio parahaemolyticus isolated from seawater, we investigated ampicillin-resistance profiles and the genetic characterization of s-lactamase (VPA0477). All of the strains studied, except one strain, were resistant to ampicillin. However, the strain that was susceptible to ampicillin had the same s-lactamase gene as the ampicillinresistant strains. We compared s-lactamase promoter region sequences among five strains, including both ampicillinresistant and -susceptible strains. In the susceptible strain, a nucleotide at position -19 in the methionine initiation codon for s-lactamase was not present in the ampicillin-resistant strains. The genes in the region containing the gene VPA0477 were present in all of the tested strains, and LA-PCR analysis showed that the distance between VPA0474 and VPA0479 in all of the V. parahaemolyticus samples was precisely 5.7 kb. In V. parahaemolyticus s-lactamase, four important structural features that are conserved in Class A s-lactamases were present in the deduced amino acid sequences. Taken together, our study demonstrates that V. parahaemolyticus s-lactamase is included in the Class A slactamase group, and some nucleotides within the promoter region are of particular importance for s-lactamase activity.