title: Biogenesis and adhesion of type 1 and P pili.
abstract: BACKGROUND
  Uropathogenic Escherichia coli (UPEC) cause urinary tract infections (UTIs) in approximately 50% of women. These bacteria use type 1 and P pili for host recognition and attachment. These pili are assembled by the chaperone-usher pathway of pilus biogenesis.
  
  
  METHODS
  The review examines the biogenesis and adhesion of the UPEC type 1 and P pili. Particular emphasis is drawn to the role of the outer membrane usher protein. The structural properties of the complete pilus are also examined to highlight the strength and functionality of the final assembly.
  
  
  CONCLUSIONS
  The usher orchestrates the sequential addition of pilus subunits in a defined order. This process follows a subunit-incorporation cycle which consists of four steps: recruitment at the usher N-terminal domain, donor-strand exchange with the previously assembled subunit, transfer to the usher C-terminal domains and translocation of the nascent pilus. Adhesion by the type 1 and P pili is strengthened by the quaternary structure of their rod sections. The rod is endowed with spring-like properties which provide mechanical resistance against urine flow. The distal adhesins operate differently from one another, targeting receptors in a specific manner. The biogenesis and adhesion of type 1 and P pili are being therapeutically targeted, and efforts to prevent pilus growth or adherence are described.
  
  
  CONCLUSIONS
  The combination of structural and biochemical study has led to the detailed mechanistic understanding of this membrane spanning nano-machine. This can now be exploited to design novel drugs able to inhibit virulence. This is vital in the present era of resurgent antibiotic resistance. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
authors.affiliation: Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
authors.forename: James
authors.initials: J
authors.lastname: Lillington
authors.affiliation: Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Geibel
authors.affiliation: Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK. Electronic address: g.waksman@ucl.ac.uk.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Waksman
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D005260:Female; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D056689:Uropathogenic Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
keywords: Chaperone; Donor-strand exchange; Macromolecular machine; Pilicides; Pilus; Usher