Characterization and sequence analysis of pilin from F-like plasmids

Area of Science:

• Molecular Biology
• Bacteriology
• Virology

Background:

• Conjugative pili mediate bacterial conjugation and are attachment sites for specific phages.
• Derepressed plasmids express conjugative pili, influencing cell-to-cell contact.
• Understanding pilus diversity is crucial for bacterial genetics and phage-host interactions.

Purpose of the Study:

• To characterize and classify conjugative pili from 13 derepressed plasmids.
• To investigate the relationship between pilus structure, retraction ability, and phage sensitivity.
• To compare pilin gene sequences with known pilus types.

Main Methods:

• Estimation of pilus number per cell and retraction ability in the presence of cyanide.
• Characterization of pilus reactivity using anti-pilus antisera and monoclonal antibodies.
• Cloning and sequencing of pilin genes from eight plasmids.

Main Results:

• Six distinct pilus groups (I-V) were defined based on sequence homology and functional characteristics.
• Pilus retraction ability correlated with sensitivity to f1 phage in some groups.
• Unique sequence features were identified in specific pilus types, affecting phage sensitivity and antigenicity.

Conclusions:

• The study provides a detailed classification of conjugative pili, revealing structural and functional diversity.
• Variations in pilin genes influence pilus retraction, phage binding, and antigenicity.
• This classification aids in understanding the evolution and mechanisms of bacterial conjugation and phage-host interactions.