Cloning and characterization of the haemolysin determinants from Aeromonas hydrophila

Publisher Website
Google Scholar
Abstract
Two haemolysin genes (AHH4 and AHH‐2) of Aeromonas hydrophila ATCC7966 were cloned into a plasmid vector in Escherichia coli K‐12. An open reading frame (ORF) of the AHH‐1 haemolysin gene was 1734 base pairs (bp). and corresponded to a protein of 577 amino acid residues. Analysis of the deduced amino sequence indicated a highly hydrophobic N‐terminal region which had the characteristics of a leader peptide. The sequence also included the ‐10 region and the ‐35 region of a promoter, and a ribosome‐ binding site upstream from the ORF. The termination site was located downstream from the ORF. The haemolysin was a thermolabile protein with the predicted molecular mass of 60 kDa. The AHH‐1 gene is distributed in various A. hydrophila and A. salmonicida strains. The nucleotide sequence of a 981 bp ORF of the AHH‐2 gene was encoded with the predicted molecular mass of 377 kDa polypeptides. The homology of the nucleotide sequence was very low between the AHH‐1 and AHH‐2 genes, and also with the aerolysin gene cloned by Howard & Buckley (19S6). No leader peptide was found in the N‐terminal region of the ORF of the AHH2 gene. The AHH‐2 gene was detected in the original strain ATCC7966, but was not detected in other tested strains of A. hydrophila and A. salmonicida.