Structure-function and biogenesis of the type IV pili

Annu Rev Microbiol. 1993;47:565-96. doi: 10.1146/annurev.mi.47.100193.003025.


Type IV pili are adhesins expressed by a number of diverse gram-negative microorganisms. These pili are related through similarities in the primary amino acid sequences of the structural subunits, a conserved assembly machinery, and a similar mechanism of transcriptional regulation. Type IV pilus assembly is preceded by proteolytic processing and N-methylation of the pilin polypeptide. This process is carried out by a novel bifunctional enzyme PilD, first identified in Pseudomonas aeruginosa. Moreover, proteins homologous with type IV pilins have been shown to function in extracellular protein secretion in gram-negative bacteria and in transformation competence in gram-positive microorganisms. Like prepilin, these proteins are also processed and N-methylated by PilD. Transcription of the genes for type IV pilins is carried out by an RNA polymerase with a minor sigma factor, RpoN. In P. aeruginosa two other regulatory elements (PilS and PilR) are required for pilin expression. RpoN, but not PilS and PilR, is required for expression of a diverse set of bacterial genes. Therefore, regulation of synthesis and posttranslational modification and assembly of type IV pili serves as a useful model for a number of diverse biological processes in the bacterial cell.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Bacteria / genetics
  • Bacteria / metabolism
  • Bacteria / ultrastructure*
  • Fimbriae, Bacterial / chemistry
  • Fimbriae, Bacterial / classification
  • Fimbriae, Bacterial / physiology*
  • Molecular Sequence Data
  • Structure-Activity Relationship