Characterization of the Moraxella catarrhalis Opa-like protein, OlpA, reveals a phylogenetically conserved family of outer membrane proteins

Michael J. Brooks, Cassie A. Laurence, Eric J. Hansen, Scott D. Gray-Owen

Research output: Contribution to journalArticle

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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 to Neisseria 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, the M. 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.

Original languageEnglish (US)
Pages (from-to)76-82
Number of pages7
JournalJournal of Bacteriology
Issue number1
Publication statusPublished - Jan 2007


ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

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