Yeast-mediated display: probing Helicobacter pylori HopQ and CEACAM1 interaction

Helicobacter pylori (H. pylori), as a Gram-negative pathogen plays a key role in causing gastritis, peptic ulcer disease, and gastric malignancies. The bacterial adhesin HopQ binds human CEACAM1, promoting adherence and CagA oncoprotein translocation. This study aimed to establish a yeast-based surface expression platform to investigate the HopQ-CEACAM1 interaction as a basis for future inhibitor screening.

The N-terminal domain of human CEACAM1 (C1ND) was displayed on the surface of Saccharomyces cerevisiae BY4741 as C1ND or C1ND-EGFP via Aga2 fusion. Constructs were introduced by electroporation and confirmed by PCR. Protein expression and localization were validated by western blot, confocal microscopy, and flow cytometry. Binding assays involved GFP-tagged HopQ and GFP-expressing H. pylori.

Western blot confirmed surface expression of C1ND and C1ND-EGFP. Confocal microscopy and flow cytometry showed strong fluorescence signals, with significantly higher mean fluorescence intensity and anti-GFP-positive yeast compared to controls (P < 0.01). Yeast-displayed C1ND specifically bound HopQ-GFP and GFP-expressing H. pylori.

Yeast surface display of CEACAM1's N-domain is an effective model for studying HopQ-CEACAM1 binding and offers potential for identifying inhibitors to block H. pylori adhesion and associated disorders.