Autor(es): Cho, WL; Tsao, SM; Hays, AR; Walter, R; Chen, JS; Snigirevskaya, ES; Raikhel, AS

Resumo: Here we report identification of a novel member of the thiol protease superfamily in the yellow fever mosquito, Aedes aegypti. It is synthesized and secreted as a latent proenzyme in a sex-, stage-, and tissue-specific manner by the fat body, an insect metabolic tissue, of female mosquitoes during vitellogenesis in response to blood feeding. The secreted, hemolymph form of the enzyme is a large molecule, likely a hexamer, consisting of 44-kDa subunits. The deduced amino acid Sequence of this 44-kDa precursor shares high similarity with cathepsin B but not with other mammalian cathepsins. We have named this mosquito enzyme vitellogenic cathepsin B (VCB). VCB decreases to 42 kDa after internalization by oocytes, In mature yolk bodies, VCB is located in the matrix surrounding the crystalline yolk protein, vitellin. At the onset of embryogenesis, VCB is further processed to 33 kDa. The embryo extract containing the 33-kDa VCB is active toward benzoyloxycarbonyl-Arg-Arg-para-nitroanilide, a cathepsin B-specific substrate, and degrades vitellogenin, the vitellin precursor. Both of these enzymatic activities are prevented by trans-epoxysuccinyl-L-leucylamido- (4-guanidino)butane (E-64), a thiol protease inhibitor. Furthermore, addition of the anti-VCB antibody to the embryonic extract prevented cleavage of vitellogenin, strongly indicating that the activated VCB is involved in embryonic degradation of vitellin.

Palavras-Chave: 29-Kda Hemocyte Proteinase; Amino-Acid-Sequences; Cysteine Proteinase; Fat-Body; Yolk Degradation; Aedes-Aegypti; Molecular-Cloning; Procathepsin-B; Bombyx-Mori; Haemonchus-Contortus

Imprenta: Journal of Biological Chemistry, v. 274, n. 19, p. 13311-13321, 1999

Identificador do objeto digital: 10.1074/jbc.274.19.13311

Descritores: Aedes aegypti - Proteins

Data de publicação: 1999

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