Structural determinants of polymerization reactivity of the P pilus adaptor subunit PapF.
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.
Verger
Denis
D
Institute of Structural and Molecular Biology, University College London, Birkbeck College, Malet Street, London WC1E 7HX, UK.
Rose
Rebecca J
RJ
Paci
Emanuele
E
Costakes
Greg
G
Daviter
Tina
T
Hultgren
Scott
S
Remaut
Han
H
Ashcroft
Alison E
AE
Radford
Sheena E
SE
Waksman
Gabriel
G
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
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