Molecular identification, characterization, and expression analysis of a novel trypsin inhibitor-like cysteine-rich peptide from the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract

AbstractTrypsin inhibitor-like cysteine-rich domain (TIL)-type protease inhibitors have been reported to inhibit proteases such as trypsin, cathepsin, elastase, and chymotrypsin, and thus play a critical role in several physiological processes. However, the information about TIL peptides in insects is limited. In the present study, a novel cysteine-rich trypsin inhibitor-like protease, designated as HaTIL2, was isolated from the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). The cDNA sequence of HaTIL2 is 470 nucleotides long, with 240 nucleotides open reading frame encoding 80 amino acid residues. The analysis of genomic DNA revealed that the full-length genomic DNA sequence of HaTIL2 was 574 bp with two exons and one intron. The predicted molecular weight of HaTIL2 is 8.632 kDa, with an isoelectric point of 4.41. The results of neighbor-joining tree demonstrated that HaTIL2 was closely related to H. armigera TIL3, DmCEI, and DsCtAPI followed by TcIMI and MdCEI. The mRNA of HaTIL2 was constitutively expressed at different levels in different stages of H. armigera. The HaTIL2 showed a high expression on different days of the pupal stage, which revealed that HaTIL2 might play a vital role during the pupal stage. Although the detailed function of HaTIL2 needs to be elucidated, the obtained results are of particular importance to open up new avenues of research into the functional studies of insect peptidase inhibitors.