The respiratory pathogen Moraxella catarrhalis adheres to epithelial cells by interacting with fibronectin through ubiquitous surface proteins A1 and A2

J Infect Dis. 2005 Sep 15;192(6):1029-38. doi: 10.1086/432759. Epub 2005 Aug 12.


Moraxella catarrhalis ubiquitous surface protein (Usp) A1 has been reported to bind fibronectin and is involved in adherence. In this study, using M. catarrhalis mutants derived from clinical isolates, we show that both UspA1 and UspA2 bind fibronectin. Recombinant truncated UspA1/A2 proteins, together with smaller fragments spanning the entire molecule, were tested for binding to fibronectin. Both UspA1 and UspA2 bound fibronectin, and the fibronectin-binding domains were located within UspA1(299-452) and UspA2(165-318). These 2 truncated proteins inhibited binding of M. catarrhalis to Chang conjunctival epithelial cells to an extent similar to that by anti-human fibronectin antibodies. Our observations show that both UspA1 and UspA2 are involved in adherence to epithelial cells via cell-associated fibronectin. The biologically active sites within UspA1(299-452) and UspA2(165-318) have therefore been suggested to be potential candidates to be included in a future vaccine against M. catarrhalis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Adhesion / physiology*
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Binding Sites
  • Cell Line
  • Epithelial Cells / microbiology*
  • Fibronectins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Moraxella catarrhalis / physiology*
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Recombinant Proteins
  • Sequence Homology, Amino Acid


  • Bacterial Outer Membrane Proteins
  • Fibronectins
  • Recombinant Proteins
  • UspA protein, Moraxella catarrhalis