Outer membrane protein P1 is the CEACAM‐binding adhesin of Haemophilus influenzae. Issue 3 (18th August 2015)

• Record Type: Journal Article
• Authors: Tchoupa, Arnaud Kengmo; Lichtenegger, Sabine; Reidl, Joachim; Hauck, Christof R.
• Is Part Of: Molecular microbiology. Volume 98:Issue 3(2015)
• Page Start: 440
• Page End: 455
• Publication Date: 2015-08-18
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.13134
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p> <italic>H</italic> <italic>aemophilus influenzae</italic> is a Gram‐negative pathogen colonizing the upper respiratory tract mucosa. <italic>H</italic><italic>. influenzae</italic> is one of several human‐restricted bacteria, which bind to carcinoembryonic antigen‐related cell adhesion molecules (CEACAMs) on the epithelium leading to bacterial uptake by the eukaryotic cells. Adhesion to CEACAMs is thought to be mediated by the <italic>H</italic><italic>. influenzae</italic> outer membrane protein (OMP) P5. However, CEACAMs still bound to <italic>H</italic><italic>. influenzae</italic> lacking OMP P5 expression, and soluble CEACAM receptor ectodomains failed to bind to OMP P5, when heterologously expressed in <italic>E</italic><italic>scherichia coli</italic>. Screening of a panel of <italic>H</italic><italic>. influenzae</italic> OMP mutants revealed that lack of OMP P1 completely abrogated CEACAM binding and supressed CEACAM‐mediated engulfment of <italic>H</italic><italic>. influenzae</italic> by epithelial cells. Moreover, ectopic expression of OMP P1 in <italic>E</italic><italic>. coli</italic> was sufficient to induce CEACAM binding and to promote attachment to and internalization into CEACAM‐expressing cells. Interestingly, OMP P1 selectively recognizes human CEACAMs, but not homologs from other mammals and this binding preference is preserved upon expression in <italic>E</italic><italic>. coli</italic>. Together, our data identify OMP P1 as the <italic>bona fide</italic> CEACAM‐binding invasin of <italic>H</italic><italic>. influenzae</italic>. This is the first report providing evidence for an involvement of the major OMP P1 of <italic>H</italic><italic>. influenzae</italic> in pathogenesis.</p> </abstract>