Identification of a novel Haemophilus influenzae protein important for adhesion to epithelial cells.
Non-typable Haemophilus influenzae (NTHi) is an important human-specific respiratory pathogen colonizing the mucosa of the upper respiratory tract. The bacterium is a common cause of acute otitis media in children and exacerbations in patients with chronic obstructive pulmonary disease (COPD). An immunoglobulin (Ig) D-lambda myeloma protein was found to detect a 16 kDa surface protein that we designated protein E (PE). The pe gene was cloned using an NTHi genomic DNA library, and a truncated PE-derived protein lacking the endogenous signal peptide (PE22-160) was synthesized and produced in large amounts in Escherichia coli. Interestingly, PE was expressed at the bacterial surface of NTHi as revealed by flow cytometry using the IgD-lambda myeloma protein or PE-specific polyclonal antibodies. A PE-deficient NTHi mutant was produced and lost 50% of its adhesive capacity as compared to the wild-type counterpart when analysed for adhesion to type II lung alveolar epithelial cells. In parallel, E. coli expressing full-length PE1-160 adhered significantly more efficiently to epithelial cells as compared to wild-type E. coli. Recombinant IgD that recognized the chemical dansyl-chloride did not interact with PE indicating that the IgD-lambda myeloma protein most likely was an antibody directed against the H. influenzae surface epitope. In conclusion, we have discovered a novel NTHi outer membrane protein with adhesive properties using an IgD-myeloma protein.
Ronander
Elena
E
Medical Microbiology, Department of Laboratory Medicine, Malmö University Hospital, Lund University, SE-205 02 Malmö, Sweden.
Brant
Marta
M
Janson
Håkan
H
Sheldon
Joanna
J
Forsgren
Arne
A
Riesbeck
Kristian
K
D018829:Adhesins, Bacterial / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D001422:Bacterial Adhesion / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004847:Epithelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D005434:Flow Cytometry; D017353:Gene Deletion; D006193:Haemophilus influenzae / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins