Host cell binding of the flagellar tip protein of Campylobacter jejuni

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Bacterial flagella are essential for motility.
• The flagellar tip protein FliD in Campylobacter jejuni is a key component of the flagellar filament.
• Understanding bacterial adhesion mechanisms is critical for combating infections.

Purpose of the Study:

• To investigate the role of Campylobacter jejuni FliD protein in host cell attachment.
• To identify the specific host cell receptors targeted by FliD.
• To elucidate the mechanism of bacterial adhesion mediated by flagella.

Main Methods:

• Live-cell imaging and confocal microscopy were used to observe bacterial-host cell interactions.
• Recombinant FliD protein binding assays were performed on intestinal epithelial cells.
• Cells with glycosylation defects and enzymatic treatments (heparinase) were employed to identify binding sites.
• Direct binding assays confirmed the interaction between FliD and heparin.

Main Results:

• Campylobacter jejuni bacteria initially contact host cells via their flagella tips.
• Recombinant FliD protein binds to intestinal epithelial cells in a dose-dependent manner.
• FliD specifically binds to glycosaminoglycans, particularly heparin, on the host cell surface.
• Blocking FliD-heparin interaction reduces bacterial attachment to host cells.

Conclusions:

• The Campylobacter jejuni flagellar tip protein FliD functions as an adhesin.
• FliD mediates bacterial attachment by interacting with host cell surface heparan sulfate.
• This interaction highlights a novel mechanism for bacterial colonization and suggests FliD as a potential therapeutic target.