Chitooligosaccharide binding to CIA17 (Coccinia indica agglutinin). Thermodynamic characterization and formation of higher order complexes

Bobbili, KB and Singh, B and Narahari, A and Bulusu, G and Surolia, A and Swamy, MJ (2019) Chitooligosaccharide binding to CIA17 (Coccinia indica agglutinin). Thermodynamic characterization and formation of higher order complexes. In: International Journal of Biological Macromolecules, 137 . pp. 774-782.

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Abstract

CIA17 is a PP2-like, homodimeric lectin made up of 17 kDa subunits present in the phloem exudate of ivy gourd (Coccinia indica). Isothermal titration calorimetric (ITC) studies on the interaction of chitooligosaccharides [(GlcNAc)2–6] showed that the dimeric protein has two sugar binding sites which recognize chitotriose with ~70-fold higher affinity than chitobiose, indicating that the binding site is extended in nature. ITC, atomic force microscopic and non-denaturing gel electrophoresis studies revealed that the high-affinity interaction of CIA17 with chitohexaose (Ka = 1.8 × 107 M−1) promotes the formation of protein oligomers. Computational studies involving homology modeling, molecular docking and molecular dynamics simulations on the binding of chitooligosaccharides to CIA17 showed that the protein binding pocket accommodates up to three GlcNAc residues. Interestingly, docking studies with chitohexaose indicated that its two triose units could interact with binding sites on two protein molecules to yield dimeric complexes of the type CIA17-(GlcNAc)6-CIA17, which can extend in length by the binding of additional chitohexaose and CIA17 molecules. These results suggest that PP2 proteins play a role in plant defense against insect/pathogen attack by directly binding with the higher chain length chitooligosaccharides and forming extended, filamentous structures, which facilitate wound sealing.

Item Type:	Journal Article
Publication:	International Journal of Biological Macromolecules
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to Elsevier B.V.
Keywords:	chitobiose; chitohexaose; chitooligosaccharide; chitotriose; Coccinia grandis agglutinin 17; oligomer; oligosaccharide; plant lectin; unclassified drug; chitosan; Coccinia indica lectin; oligosaccharide; plant lectin, Article; binding affinity; binding site; Coccinia grandis; complex formation; controlled study; molecular docking; molecular dynamics; nonhuman; protein carbohydrate interaction; sequence homology; thermodynamics; acetylation; chemistry; metabolism; protein conformation, Acetylation; Chitosan; Molecular Docking Simulation; Molecular Dynamics Simulation; Oligosaccharides; Plant Lectins; Protein Conformation; Thermodynamics
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	06 Jan 2023 05:25
Last Modified:	06 Jan 2023 05:25
URI:	https://eprints.iisc.ac.in/id/eprint/78802

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