Molecular characterization of interactions between Lectin - a protein from the common edible mushroom (Agaricus bisporus) - with dietary carbohydratesSchool of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, VIC, 3083, Australia
Lectins can be widely found in living organisms such as animals, fungi, plants, bacteria and viruses. Most lectins in plants are storage proteins and play a critical role in the defense of external threats. Lectins are either univalent or polyvalent proteins of nonimmune origin that bind reversibly and noncovalently to specific sugars on the opposing cell. Their activity originates from the ability to recognize and reversibly bind carbohydrates and glycoconjugates. The molecular mechanism of ligand binding and the binding stoichiometry between Agaricus bisporus lectin (ABL) and dietary carbohydrates are yet to be studied1,2,3.
In the present work, we applied circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), intrinsic fluorescence spectroscopy and molecular docking techniques to evaluate the interactions between ABL and dietary carbohydrates/antigen recognition agents (galactose, glucose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine).
Intrinsic fluorescence measurements with increasing concentrations of dietary carbohydrates/antigen recognition agents resulted in a considerable quenching of fluorescence intensity of the ABL solutions. This indicates that binding of the ligand has occurred and nonlinear fitting of quenching data shows that the binding strength of interactions is intermediate to strong, with galactose exhibiting the strongest molecular interactions. Circular dichroism and Fourier transform infrared analyses record alteration in the protein secondary structure with ligand binding. Molecular docking highlights the likely binding positions of each ligand to the ABL molecule further arguing for the presence of stable interactions between the protein and the ligands, which differ in the conformation of a single epimeric hydroxyl group at position four of the sugar ring. These findings give a deeper understanding of the molecular interactions between lectin from Agaricus bisporus and dietary carbohydrates providing a theoretical basis for its functionality as a nutraceutical with hypoglycemic capability.
- Tirta Ismaya, W., Tjandrawinata, R. R., & Rachmawati, H. (2020). Lectins from the edible mushroom agaricus bisporus and their therapeutic potentials. Molecules, 25(10), 2368
- Singh, R. S., Bhari, R., & Kaur, H. P. (2010). Mushroom lectins: Current status and future perspectives. Critical Reviews in Biotechnology, 30(2), 99–126.
- Condict, L., Hung, A., Ashton, J., & Kasapis, S. (2021). High-temperature binding parameters and molecular dynamics of 4-hydroxybenzoic acid and β-casein complexes, determined via the method of continuous variation and fluorescence spectroscopy. Food Hydrocolloids, 114, 106567.