Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three distinct digestive protease systems were induced in larvae of the herbivorous pest, Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), and used as a model to assess the ability of the proregion of papaya proteinase IV (PPIV; glycyl endopeptidase, EC 3.4.22.25) to act as an inhibitor of insect digestive cysteine proteinases. As shown by gelatin/PAGE and complementary inhibition assays, a recombinant form of the proregion produced in Escherichia coli inhibited a fraction of the insect proteases also inhibited by the well-characterized inhibitor of cysteine proteinases, oryzacystatin I (OCI). In contrast with OCI, the inhibitory potency of the proregion was affected by an increase of the temperature, suggesting a certain alteration of its structural integrity by the insect non-target proteases. This apparent susceptibility to proteolysis was confirmed by SDS-PAGE, after challenging the proregion with the different insect extracts. As seen on gel, selective inhibition of the insect aspartate proteinase, cathepsin D, with the inhibitor pepstatin A preserved the activity of the proregion against cysteine proteinases by preventing its hydrolysis. Taken together, these observations suggest the potential of plant protease proregions as regulators of cysteine proteinases in biotechnological systems, and show the ability of protease inhibitors to preserve the integrity of 'companion' defense-related proteins from the action of insensitive proteases in target pests.
 ...
PMID:The proregion of papaya proteinase IV inhibits Colorado potato beetle digestive cysteine proteinases. 974 62

Although several studies were carried out over the last 15 years to assess the nature and characteristics of digestive proteases in herbivorous insects, little is known about the relative importance of these enzymes in the hydrolysis of specific dietary proteins. In this study, we assessed the involvement of Colorado potato beetle (CPB; Leptinotarsa decemlineata Say, Chrysomelidae) aspartate, cysteine, and serine digestive proteinases in the degradation of two model substrates: ribulose biphosphate carboxylase/oxygenase, the major protein in potato leaves, and the pro-region of papaya proteinase IV, a cysteine protease inhibitor (PI) susceptible to proteolysis by the insect "nontarget" proteases. As shown by the use of various combinations of diagnostic PIs specific to the different classes of CPB proteinases, the insect aspartate (cathepsin D-like) proteinase activity is important in initiating the hydrolysis of both proteins when the insect is feeding on potato, while cysteine (cathepsin B/cathepsin H-like) and serine (chymotrypsin-like) proteinase activities would be involved in subsequent steps of the hydrolytic process. Similar observations were made with diet-induced variants of the insect protease system, suggesting the importance of digestive cathepsin D and the sequential hydrolysis of dietary proteins in CPB, regardless of the diet ingested. Based on these observations, a preliminary model is proposed to explain dietary protein hydrolysis in CPB, also taking into account the information currently available about the distribution of digestive endo- and exopeptidases in the midgut of CPB. The potential of a wound-induced cathepsin D inhibitor from tomato in developing CPB-resistant transgenic potato lines is also discussed, after demonstrating the "pepstatin-like" effect of a recombinant form of this proteinaceous inhibitor against the insect cathepsin D. Arch. Copyright 1999 Wiley-Liss, Inc.
 ...
PMID:Protein hydrolysis by colorado potato beetle, leptinotarsa decemlineata, digestive proteases: the catalytic role of cathepsin D 1046 59