Affiliation:
1. Department of Pediatrics, Center for Microbial Pathogenesis, Columbus Children's Research Institute, The Ohio State University College of Medicine and Public Health, Columbus, Ohio
Abstract
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.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
93 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献