title: The pilus-retraction protein PilT: ultrastructure of the biological assembly.
abstract: PilT is a biological motor required for the retraction of bacterial type IV pili. Nesseria gonorrhoeae PilT has been purified and its ultrastructure has been examined by freeze-etch electron microscopy, revealing a 115 A outer diameter, 15-35 A inner diameter ring. Aquifex aeolicus PilT crystals were obtained in a primitive hexagonal space group (unit-cell parameters a = b = 107.3, c = 68.5 A) and diffract to a minimum Bragg spacing of 2.8 A when PilT is co-crystallized with adenine nucleotides. Initial phases to 3.5 A resolution have been determined by multiwavelength anomalous dispersion and density modification. Resulting electron-density maps show a hexameric A. aeolicus PilT ring 105 A wide by 55 A high, with an inner cavity that varies in shape and width from 20 to 40 A over the height of the complex. Both PilT ultrastructures are very similar to type II and type IV secretion ATPases in overall shape, size and assembly.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, USA. forest@bact.wisc.edu
authors.forename: Katrina T
authors.initials: KT
authors.lastname: Forest
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Satyshur
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Worzalla
authors.forename: Johanna K
authors.initials: JK
authors.lastname: Hansen
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Herdendorf
mesh_terms: D000251:Adenosine Triphosphatases; D001419:Bacteria / Q000737:chemistry; D001426:Bacterial Proteins; D018360:Crystallography, X-Ray; D010861:Fimbriae, Bacterial / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D020409:Molecular Motor Proteins; D009344:Neisseria gonorrhoeae / Q000737:chemistry*; D011487:Protein Conformation; D040681:Structural Homology, Protein
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; D000251:Adenosine Triphosphatases