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The Haemophilus influenzae Hia autotransporter harbours two adhesive pockets that reside in the passenger domain and recognize the same host cell receptor
Author(s) -
Laarmann Sven,
Cutter David,
Juehne Twyla,
Barenkamp Stephen J.,
St Geme Joseph W.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03189.x
Subject(s) - bacterial adhesin , biology , microbiology and biotechnology , haemophilus influenzae , receptor , avidity , pasteurellaceae , mucociliary clearance , pilus , virulence , immunology , genetics , antigen , gene , antibiotics , linguistics , philosophy , lung
Summary Haemophilus influenzae is a human‐specific pathogen and a major source of morbidity worldwide. Infection with this organism begins with colonization of the nasopharynx, a process that probably depends on adherence to respiratory epithelium. The Hia autotransporter protein is the major adhesin ex‐pressed by a subset of non‐typeable H. influenzae strains and promotes high‐level adherence to a variety of human epithelial cell lines. In the current study, we discovered that the Hia passenger domain contains two distinct binding pockets, including one at the C‐terminal end and a second at the N‐terminal end. Competition assays revealed that the two binding pockets interact with the same host cell receptor structure, although with differing affinities. Additional experiments demonstrated that both binding domains are required for full‐level bacterial adherence. These observations are reminiscent of eukaryotic cell adhesion molecules and highlight the first example of a bacterial adhesin with two domains that participate in a bivalent interaction with identical host cell receptors. Such an interaction increases avidity, thus stabilizing bacterial adherence to the epithelial surface, despite physical forces such as coughing, sneezing and mucociliary clearance.