title: A novel protease inhibitor in Bombyx mori is involved in defense against Beauveria bassiana.
abstract: Entomopathogenic fungi, such as Beauveria bassiana, penetrate the insect cuticle using a plethora of hydrolytic enzymes including cuticle-degrading proteases and chitinases, which are important virulence factors. The insect integument and hemolymph contains a relatively high concentration of protease inhibitors, which are closely involved with defense against pathogenic microorganisms. To elucidate the molecular mechanism underlying resistance against entomopathogenic fungi and to identify a new molecular target for improving fungal resistance in the silkworm, Bombyx mori, we cloned and expressed a novel silkworm TIL-type protease inhibitor BmSPI38, which was very stable over a wide range of temperatures and pH values. An activity assay suggested that BmSPI38 potently inactivated the insecticidal cuticle-degrading enzyme (CDEP-1) produced by B. bassiana and subtilisin A produced by Bacillus licheniformis. The melanization of silkworm induced by CDEP-1 protease could also be blocked by BmSPI38. These results provided new insights into the molecular mechanisms whereby insect protease inhibitors provide resistance against entomopathogenic fungi, suggesting the possibility of using fungal biopesticides in sericulture.
authors: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China.
authors: Youshan
authors: Y
authors: Li
authors: Ping
authors: P
authors: Zhao
authors: Shiping
authors: S
authors: Liu
authors: Zhaoming
authors: Z
authors: Dong
authors: Jianping
authors: J
authors: Chen
authors: Zhonghuai
authors: Z
authors: Xiang
authors: Qingyou
authors: Q
authors: Xia
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D052982:Beauveria / Q000737:chemistry / Q000201:enzymology*; D012831:Bombyx / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D055550:Protein Stability; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D019476:Insect Proteins; D011480:Protease Inhibitors; D010447:Peptide Hydrolases