Structure of the Bacterial Sex F Pilus Reveals an Assembly of a Stoichiometric Protein-Phospholipid Complex.
Conjugative pili are widespread bacterial appendages that play important roles in horizontal gene transfer, in spread of antibiotic resistance genes, and as sites of phage attachment. Among conjugative pili, the F "sex" pilus encoded by the F plasmid is the best functionally characterized, and it is also historically the most important, as the discovery of F-plasmid-mediated conjugation ushered in the era of molecular biology and genetics. Yet, its structure is unknown. Here, we present atomic models of two F family pili, the F and pED208 pili, generated from cryoelectron microscopy reconstructions at 5.0 and 3.6 Å resolution, respectively. These structures reveal that conjugative pili are assemblies of stoichiometric protein-phospholipid units. We further demonstrate that each pilus type binds preferentially to particular phospholipids. These structures provide the molecular basis for F pilus assembly and also shed light on the remarkable properties of conjugative pili in bacterial secretion and phage infection.
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Tiago R D
TRD
Costa
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Aravindan
A
Ilangovan
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Marta
M
Ukleja
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Adam
A
Redzej
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Joanne M
JM
Santini
BSRC, School of Biology, University of St Andrews, St Andrews KY16 9AJ, UK.
Terry K
TK
Smith
Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA. Electronic address: egelman@virginia.edu.
Edward H
EH
Egelman
Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK. Electronic address: g.waksman@mail.cryst.bbk.ac.uk.
Gabriel
G
Waksman
D001287:Attachment Sites, Microbiological / Q000235:genetics; D020285:Cryoelectron Microscopy; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D005144:F Factor / Q000737:chemistry* / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008958:Models, Molecular; D009154:Mutation; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D000069320:Type V Secretion Systems / Q000737:chemistry / Q000378:metabolism
D029968:Escherichia coli Proteins; D008055:Lipids; D010743:Phospholipids; D021122:Protein Subunits; D000069320:Type V Secretion Systems
Conjugation; Cryoelectron Microscopy; Phospholipid; Pilus; Protein-phospholipid complex; Structural Biology; Type 4 Secretion System