title: Structural and functional studies of the Pseudomonas aeruginosa minor pilin, PilE.
abstract: Many bacterial pathogens, including Pseudomonas aeruginosa, use type IVa pili (T4aP) for attachment and twitching motility. T4aP are composed primarily of major pilin subunits, which are repeatedly assembled and disassembled to mediate function. A group of pilin-like proteins, the minor pilins FimU and PilVWXE, prime pilus assembly and are incorporated into the pilus. We showed previously that minor pilin PilE depends on the putative priming subcomplex PilVWX and the non-pilin protein PilY1 for incorporation into pili, and that with FimU, PilE may couple the priming subcomplex to the major pilin PilA, allowing for efficient pilus assembly. Here we provide further support for this model, showing interaction of PilE with other minor pilins and the major pilin. A 1.25 Å crystal structure of PilEΔ1-28 shows a typical type IV pilin fold, demonstrating how it may be incorporated into the pilus. Despite limited sequence identity, PilE is structurally similar to Neisseria meningitidis minor pilins PilXNm and PilVNm, recently suggested via characterization of mCherry fusions to modulate pilus assembly from within the periplasm. A P. aeruginosa PilE-mCherry fusion failed to complement twitching motility or piliation of a pilE mutant. However, in a retraction-deficient strain where surface piliation depends solely on PilE, the fusion construct restored some surface piliation. PilE-mCherry was present in sheared surface fractions, suggesting that it was incorporated into pili. Together, these data provide evidence that PilE, the sole P. aeruginosa equivalent of PilXNm and PilVNm, likely connects a priming subcomplex to the major pilin, promoting efficient assembly of T4aP.
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and.
authors.forename: Ylan
authors.initials: Y
authors.lastname: Nguyen
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and.
authors.forename: Hanjeong
authors.initials: H
authors.lastname: Harvey
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and.
authors.forename: Seiji
authors.initials: S
authors.lastname: Sugiman-Marangos
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and.
authors.forename: Stephanie D
authors.initials: SD
authors.lastname: Bell
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and.
authors.forename: Ryan N C
authors.initials: RN
authors.lastname: Buensuceso
authors.affiliation: the Department of Biochemistry, Western University, London, Ontario N6A 3K7, Canada.
authors.forename: Murray S
authors.initials: MS
authors.lastname: Junop
authors.affiliation: From the Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8S 4K1 and burrowl@mcmaster.ca.
authors.forename: Lori L
authors.identifier: http://orcid.org/0000-0003-0838-5040
authors.initials: LL
authors.lastname: Burrows
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D036781:Fimbriae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry*; D015870:Gene Expression; D017930:Genes, Reporter; D005816:Genetic Complementation Test; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D020033:Protein Isoforms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D000097573:Red Fluorescent Protein
chemical_list: D036781:Fimbriae Proteins; D008164:Luminescent Proteins; D020033:Protein Isoforms; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D000097573:Red Fluorescent Protein
keywords: Neisseria; Neisseria meningitidis; PilC1; PilY1; Pseudomonas aeruginosa (P. aeruginosa); X-ray crystallography; bacterial adhesion; bacterial pathogenesis; bacterial two-hybrid; minor pilins; pilus assembly; protein-protein interaction; twitching motility; type IV pili