Recombinant Lectin from Tepary Bean (Phaseolus acutifolius) with Specific Recognition for Cancer-Associated Glycans:...

Area of Science:

• Biochemistry
• Structural Biology
• Glycobiology

Background:

• Lectins are proteins that bind carbohydrates and play roles in biological recognition.
• Tepary bean lectins have shown potential in distinguishing between healthy and cancerous cells.
• Understanding lectin structure-function relationships is crucial for developing targeted therapies.

Purpose of the Study:

• To produce and characterize recombinant Tepary bean lectin (rTBL-1).
• To determine the three-dimensional (3D) structure of rTBL-1.
• To investigate the differential recognition of rTBL-1 for cancer-associated glycoconjugates.

Main Methods:

• Recombinant protein expression in Pichia pastoris.
• Nickel affinity chromatography for purification.
• X-ray diffraction for 3D structure determination.
• Glycan array screening and Isothermal Titration Calorimetry (ITC) for binding analysis.

Main Results:

• rTBL-1 was successfully produced (316 mg/L) and purified as a stable 120 kDa homo-tetramer.
• The 3D structure revealed canonical leguminous lectin fold with bound Ca2+ and Mn2+ ions.
• rTBL-1 specifically recognized 14 cancer-associated β1-6 branched N-glycans, with improved binding in the presence of α1-6 core fucose.
• No interaction was observed with mono- and disaccharides, indicating high specificity for larger glycans.

Conclusions:

• The determined 3D structure of rTBL-1 provides insights into its carbohydrate-binding mechanism.
• rTBL-1 exhibits selective binding towards cancer-associated N-glycans.
• This specificity suggests potential applications of rTBL-1 in cancer diagnostics or therapeutics.