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Structure of the Bordetella pertussis gene coding for the serotype 3 fimbrial subunit
F R Mooi1, A ter Avest, H G van der Heide
1Laboratory of Bacteriology, National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands.
Abstract:
Bordetella pertussis strains contain at least three distinct genes coding for fimbrial subunits, designated fim2, fim3, and fimX. The sequences of the fim2 and fimX genes have been published. Here we present the sequence of the fim3 gene. Proximal and distal to the fim3 gene, regions were observed that could function as rho-independent terminators, suggesting that the gene is not part of a larger operon. Comparison of the putative promoter regions of the fim2 and fim3 genes revealed a conserved region containing a stretch of approximately 13 C's. This region may be involved in fimbrial phase variation. A comparison of the deduced amino acid sequences of the three fimbrial subunits revealed conserved, variable, and hypervariable regions. The hypervariable regions coincided with predicted antigenic determinants. Peptides derived from the conserved regions may be incorporated into a future pertussis vaccine to induce antibodies which confer protection against strains producing different fimbrial serotypes.
Insights
Bordetella pertussis fimbrial genes fim2, fim3, and fimX were analyzed. Conserved regions in fimbrial subunits may be key for developing a broad-spectrum pertussis vaccine.
Area of Science:
- Microbiology
- Molecular Biology
- Vaccine Development
Background:
- Bordetella pertussis possesses multiple fimbrial subunit genes (fim2, fim3, fimX).
- Previous studies published the sequences for fim2 and fimX.
- The fim3 gene sequence and its regulatory elements are investigated here.
Purpose of the Study:
- To present the DNA sequence of the Bordetella pertussis fim3 gene.
- To analyze regulatory regions associated with fim3, including potential rho-independent terminators.
- To compare the sequences of fim2, fim3, and fimX fimbrial subunits and their potential role in vaccine development.
Main Methods:
- DNA sequencing of the fim3 gene.
- Bioinformatic analysis of gene sequences and promoter regions.
- Amino acid sequence comparison of fimbrial subunits.
Main Results:
- The fim3 gene sequence is presented, with identified rho-independent terminators.
- A conserved region (13 C's) in promoter regions of fim2 and fim3 suggests a role in phase variation.
- Amino acid sequence analysis revealed conserved, variable, and hypervariable regions, with hypervariable areas correlating to antigenic determinants.
Conclusions:
- The fim3 gene is likely not part of a larger operon.
- The conserved promoter region may regulate fimbrial phase variation.
- Conserved regions of fimbrial subunits offer potential targets for a broadly protective pertussis vaccine.