Open AccessCharacterization of the Moraxella catarrhalis Opa-Like Protein, OlpA, Reveals a Phylogenetically Conserved Family of Outer Membrane Proteins
Author(s) -
Michael J. Brooks,
Cassie A. Laurence,
Eric J. Hansen,
Scott D. Gray-Owen
Publication year - 2007
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00788-06
Subject(s) - moraxella catarrhalis , biology , bacterial outer membrane , moraxella (branhamella) catarrhalis , bacterial adhesin , neisseria , membrane protein , microbiology and biotechnology , conserved sequence , protein family , pilus , peptide sequence , bacteria , gene , virulence , genetics , haemophilus influenzae , escherichia coli , membrane
Moraxella catarrhalis is a human-restricted pathogen that can cause respiratory tract infections. In this study, we identified a previously uncharacterized 24-kDa outer membrane protein with a high degree of similarity toNeisseria Opa protein adhesins, with a predicted β-barrel structure consisting of eight antiparallel β-sheets with four surface-exposed loops. In striking contrast to the antigenically variable Opa proteins, theM. catarrhalis Opa-like protein (OlpA) is highly conserved and constitutively expressed, with 25 of 27 strains corresponding to a single variant. Protease treatment of intact bacteria and isolation of outer membrane vesicles confirm that the protein is surface exposed yet does not bind host cellular receptors recognized by neisserial Opa proteins. Genome-based analyses indicate that OlpA and Opa derive from a conserved family of proteins shared by a broad array of gram-negative bacteria.