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Genes of pyelonephritogenic E. coli required for digalactoside-specific agglutination of human cells
Insights
Most pyelonephritis Escherichia coli bind uroepithelial cells via digalactoside glycolipids. New pap genes (papE, papF, papG) are crucial for this binding, with papE anchoring adhesins for pilus biogenesis.
Area of Science:
- Microbiology
- Molecular Biology
- Urology
Background:
- Pyelonephritis-associated Escherichia coli (E. coli) utilize digalactoside-containing glycolipids on uroepithelial cells for adhesion.
- Pap pili are key virulence factors mediating this specific binding.
- Understanding the genetic basis of Pap pilus biogenesis is crucial for combating urinary tract infections.
Purpose of the Study:
- To investigate the roles of novel pap genes in the biogenesis and function of Pap pili.
- To elucidate the specific contributions of papE, papF, and papG gene products to bacterial adhesion and pilus assembly.
Main Methods:
- Genetic analysis of Escherichia coli strains with mutations in pap genes (papA, papE, papF, papG).
- Hemagglutination assays using whole bacterial cells and purified Pap pili to assess digalactoside-specific binding.
- Characterization of pilus formation and adhesin function in mutant strains.
Main Results:
- Mutations in papF and papG abolish digalactoside-specific agglutination in both whole cells and pilus preparations.
- A papE mutation eliminates binding in purified pili but not in whole cells, suggesting a role in adhesin anchoring.
- Combined mutations in papA and papE prevent digalactoside-specific agglutination, impacting pilus assembly.
Conclusions:
- The papF and papG gene products are essential for the digalactoside-binding activity of Pap pili.
- The papE gene product plays a critical role in anchoring adhesins, facilitating functional pilus assembly.
- These findings provide insights into the complex genetic regulation of Pap pilus biogenesis and its implications for pyelonephritis pathogenesis.
Abstract:
Most pyelonephritic Escherichia coli strains bind to digalactoside-containing glycolipids on uroepithelial cells. Purified Pap pili (pili associated with pyelonephritis) show the same binding specificity. A non-polar mutation early in the papA pilin gene abolishes formation of Pap pili but does not affect the degree of digalactoside-specific hemagglutination. Three novel pap genes, papE , papF and papG are defined in this report. The papF and papG gene products are both required for digalactoside-specific agglutination by whole bacteria cells as well as for agglutination by pilus preparations. Pili prepared from a papE mutant have lost their binding ability although whole cells from this mutant retain it, implying an adhesin anchoring role for the papE gene product. A mutant with lesions both in the papA and the papE genes does not mediate digalactoside-specific agglutination. The implications of this finding for pilus biogenesis are discussed.