Pilincontaining

Pilincontaining describes cells, typically bacteria, that express pilin proteins and assemble pili—hair-like surface filaments composed of pilin subunits. These structures extend from the cell surface and can retract or remain static, depending on their type. Pili are diverse in length, thickness, and function, but share the common role of mediating interactions between the cell and its environment.

Pili are polymerized from pilin subunits and assembled by dedicated multi-protein machinery often encoded in clustered gene sets. Major pilins form the filament core, while specialized tip or adhesin proteins at the pilus end mediate specific binding to receptors on surfaces or host tissues. Bacteria may have multiple pilus systems, including Type I, Type IV, and others, each with distinct assembly, dynamics, and functions. Type IV pili are notable for being dynamic and capable of extension and retraction, supporting twitching motility and DNA uptake. Sex pili, such as the F pilus in Escherichia coli, mediate conjugation and horizontal gene transfer.

Key functions of pili include adhesion to host cells and abiotic surfaces, initiation and maintenance of biofilms, and, in many species, genetic exchange through conjugation. Type IV pili also contribute to motility and competence, enabling bacteria to explore environments and acquire new genetic material. Because pili facilitate critical steps in colonization and virulence, they are important targets in microbiology and infectious disease research and are considered in strategies for prevention and treatment.

Examples of pilin-containing bacteria include several Gram-negative pathogens such as Neisseria spp. and Pseudomonas aeruginosa, as well as other genera that possess diverse pilus systems. Understanding pilin-containing structures helps explain how bacteria attach, move, and transfer genes within communities.