During conjugation, a pilus emerging from the donor bacterium ensnares the recipient bacterium, draws it in close, and eventually triggers the formation of a mating bridge, which establishes direct contact and the formation of a controlled pore that allows transfer of DNA from the donor to the recipient.

What pili made of?

Pili are primarily composed of oligomeric pilin proteins, which arrange helically to form a cylinder. New pilin protein molecules insert into the base of the pilus. Pili are antigenic, and genes encoding pili can be located in the bacterial chromosome or in plasmids. Pili are not locomotive structures.

What does the pilus do?

Pili are short, hair-like structures on the cell surface of prokaryotic cells. They can have a role in movement, but are more often involved in adherence to surfaces, which facilitates infection, and is a key virulence characteristic.