title: Demonstration of Type IV pilus expression and a twitching phenotype by Haemophilus influenzae.
abstract: Haemophilus influenzae is considered a nonmotile organism that expresses neither flagella nor type IV pili, although H. influenzae strain Rd possesses a cryptic pilus locus. We demonstrate here that the homologous gene cluster pilABCD in an otitis media isolate of nontypeable H. influenzae strain 86-028NP encodes a surface appendage that is highly similar, structurally and functionally, to the well-characterized subgroup of bacterial pili known as type IV pili. This gene cluster includes a gene (pilA) that likely encodes the major subunit of the heretofore uncharacterized H. influenzae-expressed type IV pilus, a gene with homology to a type IV prepilin peptidase (pilD) as well as two additional uncharacterized genes (pilB and pilC). A second gene cluster (comABCDEF) was also identified by homology to other pil or type II secretion system genes. When grown in chemically defined medium at an alkaline pH, strain 86-028NP produces approximately 7-nm-diameter structures that are near polar in location. Importantly, these organisms exhibit twitching motility. A mutation in the pilA gene abolishes both expression of the pilus structure and the twitching phenotype, whereas a mutant lacking ComE, a Pseudomonas PilQ homologue, produced large appendages that appeared to be membrane bound and terminated in a slightly bulbous tip. These latter structures often showed a regular pattern of areas of constriction and expansion. The recognition that H. influenzae possesses a mechanism for twitching motility will likely profoundly influence our understanding of H. influenzae-induced diseases of the respiratory tract and their sequelae.
authors.affiliation: Department of Pediatrics, Columbus Children's Research Institute, Center for Microbial Pathogenesis, The Ohio State University College of Medicine and Public Health, 700 Children's Dr., Columbus, OH 43205-2696, USA. BakaletL@pediatrics.ohio-state.edu
authors.forename: Lauren O
authors.initials: LO
authors.lastname: Bakaletz
authors.forename: Beth D
authors.initials: BD
authors.lastname: Baker
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Jurcisek
authors.forename: Alistair
authors.initials: A
authors.lastname: Harrison
authors.forename: Laura A
authors.initials: LA
authors.lastname: Novotny
authors.forename: James E
authors.initials: JE
authors.lastname: Bookwalter
authors.forename: Rachna
authors.initials: R
authors.lastname: Mungur
authors.forename: Robert S
authors.initials: RS
authors.lastname: Munson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002675:Child, Preschool; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009068:Movement; D005810:Multigene Family; D010033:Otitis Media / Q000382:microbiology; D010641:Phenotype; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D036781:Fimbriae Proteins
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