Skip to main content
ARS Home » Research » Publications at this Location » Publication #105053
Title: MOLECULAR CLONING OF A CDNA THAT ENCODES A CATHEPSIN L-LIKE CYSTEINE PROTEINASE FROM ALFALFA WEEVIL (HYPERA POSTICA) MIDGUT CYSTEINE PROTEINASE FROM ALFALFA WEEVIL (HYPERA POSTICA) MIDGUT

Author
item WILHITE, STEPHEN - GENBANK (PRIVATE INDUST)
item ELDEN, THOMAS - USDA, ARS (RETIRED)
item Smigocki, Anna

Submitted to: Genbank
Publication Type: Other
Publication Acceptance Date: 10/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Insects rely on a variety of midgut proteinases to catalyze the release of free amino acids from dietary protein and thereby provide nutrients essential for normal growth and development. A potential for insect control involves the expression of proteinase inhibitor (PI) genes in transgenic plants. However, insects have revealed an ability to compensate efor lost proteinolytic activity by enhancing production of proteinases insensitive to the introduced PI. Thus, there is a need to characterize the individual proteolytic enzymes within an insect in order to pursue a directed control strategy in which each proteolytic activity is specifically targeted for inhibition. We are conducting both biochemical and molecular cloning experiments to elucidate the digestive proteinases of Hypera postica. The large majority (70-80%) of proteolytic activity appears to result from cysteine proteinases in the midgut extract, as revealed by inhibition of the enzymatic activity with class-specific protease inhibitors. Of interest from the standpoint of pest control, the recombinant rice inhibitors OCI and OCII were similarly effective at inhibiting proteolytic activity as the potent, irreversible cysteine proteinase inhibitor E-64. One cysteine proteinase clone has been identified in a random sampling of 10 lambda clones from H. Postica midgut- specific cDNA library. DNA sequencing of the insert has revealed a full-length cDNA (hcp1) encoding a predicted protein (HCP1) of 324 amino acids. This putative digestive enzyme is highly similar to cathepsin L-type cysteine proteases and is predicted to play an import role in the assimilation of dietary protein in the alfalfa weevil.