Decoding the roles of pilotins and accessory proteins in secretin escort services

FEMS Microbiol Lett. 2012 Mar;328(1):1-12. doi: 10.1111/j.1574-6968.2011.02464.x. Epub 2011 Dec 8.


Secretins are channels that allow translocation of macromolecules across the outer membranes of Gram-negative bacteria. Virulence, natural competence, and motility are among the functions mediated by these large oligomeric protein assemblies. Filamentous phage also uses secretins to exit their bacterial host without causing cell lysis. However, the secretin is only a part of a larger membrane-spanning complex, and additional proteins are often required for its formation. A class of outer membrane lipoproteins called pilotins has been implicated in secretin assembly and/or localization. Additional accessory proteins may also be involved in secretin stability. Significant progress has recently been made toward deciphering the complex interactions required for functional secretin assembly. To allow for easier comparison between different systems, we have classified the secretins into five different classes based on their requirements for proteins involved in their assembly, localization, and stability. An overview of pilotin and accessory protein structures, functions, and characterized modes of interaction with the secretin is presented.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacterial Outer Membrane Proteins / metabolism*
  • DNA Transformation Competence
  • Gram-Negative Bacteria / genetics
  • Gram-Negative Bacteria / pathogenicity
  • Gram-Negative Bacteria / physiology*
  • Locomotion
  • Macromolecular Substances / metabolism
  • Membrane Transport Proteins / metabolism*
  • Models, Biological
  • Models, Molecular
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Multimerization
  • Virus Release


  • Bacterial Outer Membrane Proteins
  • Macromolecular Substances
  • Membrane Transport Proteins