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Gene analysis of Vibrio cholerae NAGV14 pilus and its distribution
1Department of Bacteriology, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
Abstract:
Adhesive pilus of Vibrio cholerae 034, strain NAGV14, was genetically analyzed. The deduced amino acid (aa) sequence of the major pilin structural gene (VcfA) was 67% homologous to the MshA pilin in the N-terminal region, but no homology was found in the C-terminal region which contained the antigenic epitopes. Upstream and downstream flanking regions examined were highly homologous to mshB and mshC of the MSHA (mannose-sensitive hemagglutinin) gene locus. A short leader sequence and a pair of cysteines near the C-terminus which are the characteristics of type 4a pilus family were found. The major pilin structural gene of NAGV14 was compared to that of a strain V10 producing non-adhesive pili. The deduced aa sequences showed 60% homology, and the distance between two cysteines in the C-terminal region was different. A total of 177 V. cholerae strains were investigated for the presence of a type 4 pilus gene locus by PCR, and 95% were positive. The major pilin gene of NAGV14 was detected in 4 of 93 V. cholerae non-O1, non-0139 strains tested, but none of the V. cholerae O1 and O139 (72 and 12 strains, respectively). Our result suggested that a type 4 pilus gene locus similar to the MSHA gene locus is widely distributed among V. cholerae strains. We proposed naming this type 4 pilus gene locus the VCF (for V. cholerae flexible pili) gene locus.
Insights
A new type 4 pilus gene locus, named VCF (Vibrio cholerae flexible pili), is widely distributed in Vibrio cholerae strains. This locus is essential for pilus structure and function, differing between adhesive and non-adhesive strains.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Adhesive pili play crucial roles in bacterial adhesion and pathogenesis.
- The mannose-sensitive hemagglutinin (MSHA) gene locus is involved in type 4 pilus assembly in Vibrio cholerae.
- Understanding the genetic basis of pilus variation is key to deciphering Vibrio cholerae virulence.
Purpose of the Study:
- To genetically analyze the adhesive pilus of Vibrio cholerae strain NAGV14.
- To investigate the distribution of type 4 pilus gene loci in various Vibrio cholerae strains.
- To characterize the genetic differences between adhesive and non-adhesive pili in Vibrio cholerae.
Main Methods:
- Genetic analysis of the major pilin structural gene (VcfA) in Vibrio cholerae NAGV14.
- Amino acid sequence comparison with known pilins (e.g., MshA).
- Polymerase Chain Reaction (PCR) to detect type 4 pilus gene loci in 177 Vibrio cholerae strains.
Main Results:
- The VcfA sequence showed homology to MshA in the N-terminal region but differed in the C-terminal antigenic epitopes.
- Upstream and downstream flanking regions were homologous to mshB and mshC.
- A type 4a pilus characteristic short leader sequence and C-terminal cysteines were identified.
- Vibrio cholerae NAGV14 VcfA showed 60% homology to a non-adhesive pilin, with differences in cysteine spacing.
- 95% of 177 Vibrio cholerae strains possessed a type 4 pilus gene locus.
- The NAGV14 major pilin gene was found in non-O1, non-O139 strains but not in O1 or O139 strains.
Conclusions:
- A type 4 pilus gene locus, proposed as VCF (Vibrio cholerae flexible pili), is widely distributed among Vibrio cholerae.
- The VCF locus shares similarities with the MSHA locus but exhibits variations potentially influencing pilus adhesiveness.
- The distribution of the VCF locus varies among Vibrio cholerae serogroups.