title: The platform protein is essential for type IV pilus biogenesis.
abstract: A systematic genetic analysis was performed to identify the inner membrane proteins essential for type IV pilus (T4P) expression in Pseudomonas aeruginosa. By inactivating the retraction aspect of pilus function, genes essential for T4P assembly were discriminated. In contrast to previous studies in the T4P system of Neisseria spp., we found that components of the inner membrane subcomplex consisting of PilMNOP were not essential for surface pilus expression, whereas the highly conserved inner membrane protein PilC was essential. Here, we present data that PilC may coordinate the activity of cytoplasmic polymerization (PilB) and depolymerization (PilT) ATPases via their interactions with its two cytoplasmic domains. Using in vitro co-affinity purification, we show that PilB interacts with the N-terminal cytoplasmic domain of PilC. We hypothesized that PilT similarly interacts with the PilC C-terminal cytoplasmic domain. Overexpression of that domain in the wild-type protein reduced twitching motility by ∼50% compared with the vector control. Site-directed mutagenesis of conserved T4P-specific residues in the PilC C-terminal domain yielded mutant proteins that supported wild-type pilus assembly but had a reduced capacity to support twitching motility, suggesting impairment of putative PilC-PilT interactions. Taken together, our results show that PilC is an essential inner membrane component of the T4P system, controlling both pilus assembly and disassembly.
authors: Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1.
authors: Herlinder K
authors: HK
authors: Takhar
authors: Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1.
authors: Kevin
authors: K
authors: Kemp
authors: Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1.
authors: Melissa
authors: M
authors: Kim
authors: Program in Molecular Structure & Function, The Hospital for Sick Children, and the Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada. Electronic address: howell@sickkids.ca.
authors: P Lynne
authors: PL
authors: Howell
authors: Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1. Electronic address: burrowl@mcmaster.ca.
authors: Lori L
authors: LL
authors: Burrows
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D036781:Fimbriae Proteins / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D020409:Molecular Motor Proteins; D011108:Polymers; D011506:Proteins; C079208:pilC protein, Neisseria gonorrhoeae; D036781:Fimbriae Proteins; D000251:Adenosine Triphosphatases