title: Structural determinants of polymerization reactivity of the P pilus adaptor subunit PapF.
abstract: P pili are important adhesive fibers involved in kidney infection by uropathogenic Escherichia coli. Pilus subunits are characterized by a large groove resulting from lack of a beta strand. Polymerization of pilus subunits occurs via the donor-strand exchange (DSE) mechanism initiated when the N terminus of an incoming subunit interacts with the P5 region/pocket of the previously assembled subunit groove. Here, we solve the structure of the PapD:PapF complex in order to understand why PapF undergoes slow DSE. The structure reveals that the PapF P5 pocket is partially obstructed. MD simulations show this region of PapF is flexible compared with its equivalent in PapH, a subunit that also has an obstructed P5 pocket and is unable to undergo DSE. Using electrospray-ionization mass spectrometry, we show that mutations in the P5 region result in increased DSE rates. Thus, partial obstruction of the P5 pocket serves as a modulating mechanism of DSE.
authors.affiliation: Institute of Structural and Molecular Biology, University College London, Birkbeck College, Malet Street, London WC1E 7HX, UK.
authors.forename: Denis
authors.initials: D
authors.lastname: Verger
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Rose
authors.forename: Emanuele
authors.initials: E
authors.lastname: Paci
authors.forename: Greg
authors.initials: G
authors.lastname: Costakes
authors.forename: Tina
authors.initials: T
authors.lastname: Daviter
authors.forename: Scott
authors.initials: S
authors.lastname: Hultgren
authors.forename: Han
authors.initials: H
authors.lastname: Remaut
authors.forename: Alison E
authors.initials: AE
authors.lastname: Ashcroft
authors.forename: Sheena E
authors.initials: SE
authors.lastname: Radford
authors.forename: Gabriel
authors.initials: G
authors.lastname: Waksman
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003198:Computer Simulation; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D036781:Fimbriae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D033903:Periplasmic Proteins / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: C078802:AtpA protein, E coli; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C084330:PapD protein, E coli; C534235:PapF protein, E coli; C120849:PapK protein, bacteria; D033903:Periplasmic Proteins; D036781:Fimbriae Proteins; D006180:Proton-Translocating ATPases; C101709:AtpH protein, E coli