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Analysis of the structural gene encoding a hemolysin in Vibrio mimicus
M M Rahman1, S Miyoshi, K Tomochika
1Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Microbiology and Immunology
|January 1, 1997
Summary
Vibrio mimicus produces an enterotoxic hemolysin. Its gene sequence is similar to Vibrio cholerae hemolysin, suggesting a similar two-step processing mechanism for the mature 63 kDa protein.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Vibrio mimicus, an environmental bacterium, secretes a 63 kDa hemolysin.
- This hemolysin exhibits enterotoxicity in animal models.
- Understanding the genetic basis and processing of this virulence factor is crucial.
Purpose of the Study:
- To determine the nucleotide sequence of the V. mimicus hemolysin structural gene.
- To elucidate the processing pathway of the V. mimicus hemolysin.
- To compare the V. mimicus hemolysin gene and protein with known homologs, particularly from V. cholerae.
Main Methods:
- DNA sequencing to determine the open reading frame (ORF) of the hemolysin gene.
- Amino acid sequencing of the purified hemolysin using Edman degradation.
- Bioinformatic analysis of the deduced amino acid sequence for signal peptides and processing sites.
Main Results:
- A 2,232 bp ORF was identified, encoding a 744 amino acid peptide (83,903 Da).
- The V. mimicus hemolysin gene sequence shows high similarity to the V. cholerae el tor hlyA gene.
- N-terminal sequencing indicated that the mature 63 kDa hemolysin results from the removal of the first 151 amino acids, yielding a 65,972 Da protein, and a 24 amino acid signal sequence was identified.
Conclusions:
- The V. mimicus hemolysin gene is homologous to the V. cholerae hemolysin gene.
- A two-step processing mechanism, similar to that of V. cholerae hemolysin, is likely involved in generating the mature V. mimicus hemolysin.
- This study provides insights into the molecular basis of V. mimicus pathogenicity.