title: Biochemical characterization and functional analysis of the POU transcription factor POU-M2 of Bombyx mori.
abstract: POU-M2 is a homeodomain transcription factor which plays important roles in the development and silk synthesis of Bombyx mori. In this study, we expressed, purified and characterized POU-M2 and studied its transcription regulation on fibroin heavy chain gene of Bombyx mori. Gel filtration showed POU-M2 existed as a dimer in solution. Far-UV circular dichroism spectra indicated POU-M2 had a well-defined α-helix structure and the α-helix content was about 26.4%. The thermal unfolding transition of POU-M2 was a cooperative process. Tm, ΔH and ΔS were 45.15 ± 0.2 °C, 138.4 ± 0.5 KJ/mol and 0.4349 ± 0.04 KJ/(mol·K), respectively. Western blotting analysis indicated the expression level of POU-M2 increased slightly from day 3 to day 7 of the fifth instar larvae in the posterior silk gland. POU-M2 was positioned in the nucleus of cells. The luciferase reporter assay demonstrated POU-M2 could stimulate the promoter activity of fibroin heavy chain gene, and the activation effect was dependent on the amount of POU-M2. Our study suggested POU-M2 may be involved in the transcriptional regulation of fibroin heavy chain gene. These findings expand toward a better understanding of the structure of POU-M2 and its function in silk synthesis of Bombyx mori.
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China.
authors: Lina
authors: L
authors: Liu
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China.
authors: Yu
authors: Y
authors: Li
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China; Key Sericultural Laboratory of Ministry of Agriculture, College of Biotechnology, Southwest University, Beibei, Chongqing 400715, China.
authors: Yejing
authors: Y
authors: Wang
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China.
authors: Peng
authors: P
authors: Zhao
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China.
authors: Shuguang
authors: S
authors: Wei
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China.
authors: Zhenzhen
authors: Z
authors: Li
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China; Key Sericultural Laboratory of Ministry of Agriculture, College of Biotechnology, Southwest University, Beibei, Chongqing 400715, China.
authors: Huaipu
authors: H
authors: Chang
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China; Key Sericultural Laboratory of Ministry of Agriculture, College of Biotechnology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: hehuawei@swu.edu.cn.
authors: Huawei
authors: H
authors: He
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D005349:Fibroins / Q000235:genetics; D005786:Gene Expression Regulation; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050809:POU Domain Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D017433:Protein Structure, Secondary; D047011:Silk / Q000096:biosynthesis
chemical_list: D019476:Insect Proteins; D050809:POU Domain Factors; D047011:Silk; D005349:Fibroins
keywords: Biochemical characterization; Fibroin heavy chain; POU-M2; Transcriptional regulation