title: Functional characterization of the aspartic proteinase cathepsin D in the beet armyworm (Spodoptera exigua).
abstract: In insects, proteolytic enzymes are involved in food digestion and the metamorphosis process. In the present study, the full-length cDNA of an aspartic proteinase, Spodoptera exigua cathepsin D (SeCatD), was cloned, and its functions in metamorphosis were characterized. SeCatD contains an open reading frame of 1152 nucleotides, encoding a 384-amino acid polypeptide including a signal peptide and two functional domains (family A1 propeptide of amino acids (19-45) and a cathepsin D-like domain of 327 amino acids (55-381)). Three-dimensional structure analysis indicated that Asp66 and Asp251 may play important role in hydrolysis. Recombinant SeCatD was expressed in Sf9 insect cells and verified via SDS-PAGE and Western blot, the molecular mass of the expressed SeCatD was approximately 42kDa. The enzyme had an optimal pH value of 3 for activity. In addition, the tissue expression profile of SeCatD during metamorphosis was obtained, and the data demonstrated that SeCatD was expressed increasingly in the fat body and midgut, but not in the epidermis. Finally, injection of dsRNA-SeCatD into the fifth-instar larvae significantly reduced SeCatD expression and larvae survival rate compared to a dsRNA-GFP treatment. These data imply that SeCatD may function during metamorphosis and may represent a target for insect control.
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Tinghao
authors.initials: T
authors.lastname: Kang
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Ruoheng
authors.initials: R
authors.lastname: Jin
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Hu
authors.initials: H
authors.lastname: Wan
authors.affiliation: College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China; College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea. Electronic address: brjin@dau.ac.kr.
authors.forename: Byung Rae
authors.initials: BR
authors.lastname: Jin
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China. Electronic address: jianhl@mail.hzau.edu.cn.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D002402:Cathepsin D / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005216:Fat Body / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism; D007814:Larva / Q000378:metabolism; D000072417:Protein Domains; D061987:Sf9 Cells; D018411:Spodoptera / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D019476:Insect Proteins; D002402:Cathepsin D
keywords: Aspartic proteinase; Beet armyworm; Cathepsin D; Metamorphosis; RNAi; Spodoptera exigua