title: Role of Moraxella catarrhalis outer membrane protein CD in bacterial cell morphology and autoaggregation.
abstract: Moraxella catarrhalis, an important pathogen in the human respiratory tract, causes otitis media and lower respiratory tract infections. M. catarrhalis outer membrane protein CD (OMPCD) is a major heat-modifiable OMP with demonstrable potential as a vaccine candidate. The gene encoding OMPCD of M. catarrhalis strains was subjected to nucleotide sequence analysis and then inactivated by insertional mutagenesis. The ompCD mutant strains exhibited a modest growth defect in comparison with the wild-type strains. In optical microscopy and scanning/transmission electron microscopy examinations, regarding morphology, the cell size and cell wall of the ompCD mutant strains were significantly larger and thinner, respectively, than those of the wild-type strain. Furthermore, the ompCD mutant strains exhibited significant autoaggregation and increased surface hydrophobicity, in addition to a reduction in the adherence to HEp-2 cells, compared to the wild-type strains. Strains repaired by replacing the mutated ompCD gene exhibited phenotypic characteristics very similar to those of the wild-type strains. These results indicate that M. catarrhalis OMPCD, in addition to its functions related to bacterial growth and adherence to human epithelial cells, plays a very important role in bacterial physiology and pathogenesis, including aspects such as stabilizing bacterial cell morphology and preventing autoaggregation by reducing surface hydrophobicity.
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan. r-saito.mi@tmd.ac.jp
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Saito
authors.forename: Shiho
authors.initials: S
authors.lastname: Matsuoka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Fujinami
authors.forename: Shotaro
authors.initials: S
authors.lastname: Nonaka
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kubota
authors.forename: Noboru
authors.initials: N
authors.lastname: Okamura
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001422:Bacterial Adhesion; D001483:Base Sequence; D056945:Hep G2 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D001936:Moraxella catarrhalis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016254:Mutagenesis, Insertional; D009154:Mutation; D012141:Respiratory Tract Infections / Q000382:microbiology; D017422:Sequence Analysis, DNA
chemical_list: D018829:Adhesins, Bacterial; C484698:outer membrane protein CD, Moraxella catarrhalis