Functional characterization of a potent antimicrobial and insecticidal chitin binding protein from seeds of Iberis umbellata L.

Abstract

Chitin-binding proteins belong to the 2S albumin family and are helped in the plant defense, especially against fungal pathogens. A chitin-binding protein, Iu-CBP, has been identified and characterized from Iberis umbellata seeds. The purified form of this protein showed approximately an 11 kDa band under non-reduced condition on SDS-PAGE. LC-MS/MS provided a single fragment of amino acid sequence of 23 residues (QAVQSAQQQQGQVGPQQVGHMYR). UniProtKB database showed 100% sequence similarity with Moringa oleifera chitin-binding protein (Mo-CBP3-1) which classically contained two proteolytically matured alpha-helical chains linked by disulfide bonds along surfaced Arginines responsible for antimicrobial activity. Iu-CBP showed antimicrobial activity against bacterial pathogens i.e Bacillus subtilis, Xanthomonas oryzae, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa at concentrations of 5.0 and 10.0 mu g per disc. Similarly, a 20 mu g/disc dose of Iu-CBP inhibited the mycelial growth of Aspergillus flavus. At a concentration of 3.0 mg/ml, Iu-CBP had a significant reduction in progeny population of Sitophilus oryzae and Tribolium castaneum. Chitin-binding proteins have historically been studied as a source of carbon and nitrogen in plants; more recently, their thermostability, antimicrobial and insecticidal properties, along with their water sterilizing qualities have attracted the interest of the scientific community.