Isolation, Identification and Characterization of a New Type of Lectin with α-Amylase Inhibitory Activity in Chickpea (Cicer arietinum L.)

Abstract

Plant lectins are a group of highly diverse proteins that possess at least one non-catalytic domain that binds reversibly to a specific mono- or oligosaccharide. So far, only seven members in the lectin-arcelin-αAI1 supergene family in legume lectins have been reported to have inhibitory activity of α-amylases. A proteinaceous α-amylase inhibitor was isolated and purified using Ammonium sulfate precipitation (ASP), Ion exchange chromatography (IEC) and Reversed phase liquid chromatography (RPLC) from the mature seeds of chickpea. Identification by Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS-MS) indicated that the purified proteinaceous α-amylase inhibitor was a chickpea lectin CAL in GenBank (accession No. AGL46982.1). CAL had 227 aa containing a hemopexin- like repeats domain and was a cytoplasm protein. It had very low (<17%) identity with seven members in the lectin-arcelin-aAI1 supergene family in legumes that have α-amylase inhibitory activity. The purified CAL derived from prokaryotic expression was confirmed to have inhibitory activity against various α-amylases. The inhibitory activity of CAL against various α-amylases was severely affected by temperature, pH, incubation time, substrate concentration and CAL protein concentration. Feeding CAL reduced the weight of potato beetle larvae by 27.21% (P<0.05) and survival rate by 6.67% (P>0.05). Our results indicated that CAL is a new type of lectin with inhibitory activity against α-amylases in legume lectins, which can be used as a candidate in genetic engineering for breeding for pest resistance.