Related Experiment Video

Updated: Apr 7, 2026

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
11:33

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking

Published on: December 17, 2013

6.6K

Outer membrane protein P1 is the CEACAM-binding adhesin of Haemophilus influenzae

Arnaud Kengmo Tchoupa1, Sabine Lichtenegger2, Joachim Reidl2

  • 1Lehrstuhl für Zellbiologie, Universität Konstanz, Konstanz, Germany.

Molecular Microbiology
|July 17, 2015
PubMed

Insights

Haemophilus influenzae uses outer membrane protein P1 to bind human CEACAMs, facilitating bacterial entry into epithelial cells. This study identifies OMP P1 as the key invasin, crucial for H. influenzae pathogenesis.

Area of Science:

  • Microbiology
  • Cell Biology
  • Pathogenesis

Background:

  • Haemophilus influenzae is a Gram-negative pathogen that colonizes the upper respiratory tract.
  • Bacterial uptake into epithelial cells is mediated by binding to carcinoembryonic antigen-related cell adhesion molecules (CEACAMs).
  • Outer membrane protein P5 was previously suspected to mediate CEACAM binding.

Purpose of the Study:

  • To identify the specific outer membrane protein responsible for Haemophilus influenzae binding to CEACAMs.
  • To elucidate the role of this protein in bacterial invasion of epithelial cells.
  • To determine the specificity of the CEACAM-binding interaction.

Main Methods:

  • Screening of Haemophilus influenzae outer membrane protein mutants for CEACAM binding.
  • Heterologous expression of outer membrane proteins in Escherichia coli.
  • Assessing bacterial attachment and internalization into CEACAM-expressing epithelial cells.

Main Results:

  • Lack of outer membrane protein P1 abrogated CEACAM binding and epithelial cell engulfment.
  • Ectopic expression of OMP P1 in E. coli induced CEACAM binding and cell internalization.
  • OMP P1 selectively binds human CEACAMs, not homologs from other mammals.

Conclusions:

  • Outer membrane protein P1 is the bona fide CEACAM-binding invasin of Haemophilus influenzae.
  • OMP P1 plays a critical role in H. influenzae pathogenesis by mediating CEACAM-dependent invasion.
  • This finding represents the first evidence for the involvement of OMP P1 in H. influenzae pathogenesis.

More Related Videos

Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution10:53

Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution

Published on: January 16, 2017

9.6K
Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance10:55

Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance

Published on: October 16, 2018

8.7K

Related Concept Videos

Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
4.6K
Fimbriae, Pili, and Axial Filaments01:28

Fimbriae, Pili, and Axial Filaments

Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
3.1K
Structure of Cadherins01:25

Structure of Cadherins

The cadherins were one of the first cell adhesion molecules discovered; the term “cadherins”   is based on their calcium-dependent adhering properties. The first cadherins discovered on the epithelial, neuronal, and placental cells were named E-cadherin, P-cadherin, and N-cadherin, respectively. These classical cadherins share sequence and structural similarities. Other cadherins, including those involved in cell signaling, are grouped into non-classical cadherins. This...
5.2K
Adherens Junctions01:24

Adherens Junctions

Strong contact points between adjacent cells anchor them to each other, forming tissues. Such anchoring junctions are of two types –  adherens junctions and desmosomes. Adherens junctions are abundant in tissues such as  epithelium and endothelium, forming a continuous zone of adhesion called the adhesion belt. In other tissues, such as  heart muscle, they appear as clusters, linking the cells to produce coordinated heart muscle contraction.
Adherens Junctions are Dynamic
7.8K
Leaky Scanning02:28

Leaky Scanning

During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA.  Marilyn Kozak discovered that the sequence RCCAUGG (where R...
5.9K
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
4.7K