Nucleotide sequences and comparison of the hemolysin determinants of Vibrio cholerae El Tor RV79(Hly+) and RV79(Hly-) and classical 569B(Hly-)

Abstract

We determined the nucleotide sequences of the hemolysin structural gene, hlyA, of Vibrio cholerae El Tor biotype strains RV79(Hly+) and RV79(Hly-) and the hly determinant of the nonhemolytic classical biotype strain 569B(Hly-). The sequences of the hlyA gene from El Tor strains RV79(Hly+) and RV79(Hly-) have an identical 2,223-base open reading frame which is predicted to encode an 81,977-dalton precursor form of hemolysin. This value is in excellent agreement with the 84,000-Mr hemolysin described in the earlier report of Goldberg and Murphy (S. L. Goldberg and J. R. Murphy, J. Bacteriol. 162:35-41, 1985). In contrast, the sequence of the hly determinant of the classical 569B(Hly-) strain has an 11-base-pair deletion within the hlyA structural gene. In this instance the hly determinant is predicted to encode a 26,765-dalton precursor form of a truncated hemolysin. In each case, the regulatory region encoding the putative hlyA promoter and the predicted 25-amino-acid signal sequence are identical.

The (QxW)3 domain: A flexible lectin scaffold

“…I. : cholerue hemolysin sequences have also been reported by Alm et al (1988) and Rader and Murphy (1988).…”

Transcription of the Vibrio cholerae haemolysin gene, hlyA, and cloning of a positive regulatory locus, hlyU

“…Haemolytic (Hly*^) and non-haemolytic (Hly") variants of the El Tor strain RV79 have identical htyA nucieotide sequences {Rader and Murphy, 1988). and hlyA mRNA is detected in both strains {Rader and Murphy.…”

Cloning and sequencing of a novel hemolysis gene of Vibrio cholerae

“…V. cholerae has several hemolysin genes including El Tor hemolysin gene (hlyA) [15,19,20], tdh [l] and hemolysin II [2], but, nucleotide sequencing showed that hlx was different from these genes and any other kinds of toxin genes in EMBL data bank. hL\: encoded a much smaller polypeptide than hlyA; while HlyA is about 80 kDa [15,18,19], molecular mass of the putative polypeptide encoded by hLu is only 10 45 1. Further, about 30 highly hydrophobic amino acids found in the Nterminal of Hlx may act as a signal peptide, although the total amino acids are only 92 residues.…”

“…Eightbase pairs upstream from the initiation codon (ATG), a sequence (AGAA) resembling of Shine-Dalgamo sequence [17] was found. This gene differs from those of El Tor hemolysin [15,18,19] and TDH [l] of V. colerae, and had no significant homology to any other kinds of toxin genes in EMBL data bank.…”