Diverse Enzymatic Specificities of Digestive Proteases, 'Intestains', Enable Colorado Potato Beetle Larvae to Counteract the Potato Defence Mechanism
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Abstract
In response to insect attack, high levels of proteinase inhibitors are synthesised in potato leaves. This can cause inefficient protein digestion in insects, leading to reduced growth, delayed development and lower fecundity. It has been suggested that Colorado potato beetle overcomes this defence mechanism by inducing the production of a set of cysteine proteases that are resistant to potato proteinase inhibitors. Experiments with gut extracts showed that these proteases have unusual inhibition profiles as they are not inhibited by most of the cystatins but are strongly inhibited by thyropins. In this study we have isolated three cysteine proteases from adapted guts of Colorado potato beetle larvae, named intestains 1, 2 and 3, the first cysteine proteases known to be involved in extracellular protein digestion. The N-terminal sequences suggest their classification into the papain family. Intestains differ in substrate specificities and inhibitory profiles. Their substrate specificities suggest that intestains 1 and 2 are general digestive enzymes, while intestain 3 has a more specific function. The inhibitory profile of intestain 1 is similar to that of proteases of the papain family. However, the K1 values for the interaction of intestain 2 with the same set of inhibitors are several hundred fold higher, which would enable the enzyme to circumvent the potato defence mechanism characterised by high concentrations of protease inhibitors in attacked potato leaves. A further, different strategy of the Colorado potato beetle to avoid potato defence is exhibited by intestain 3, which is able to cleave off the N-terminus of model cystatin and thus inactivate the inhibitor. These results suggest that the Colorado potato beetle combines different strategies to counteract plant defence mechanisms.
Copyright © 2003 by Walter de Gruyter GmbH & Co. KG
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- Diverse Enzymatic Specificities of Digestive Proteases, 'Intestains', Enable Colorado Potato Beetle Larvae to Counteract the Potato Defence Mechanism
- Protease Inhibitors Prevent Plasminogen-Mediated, But Not Pemphigus Vulgaris-Induced, Acantholysis in Human Epidermis
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Articles in the same Issue
- Obituary
- Thrombin Signaling in the Brain: The Role of Protease-Activated Receptors
- Transcriptional Repression of the Human p53 Gene by Hepatitis B Viral Core Protein (HBc) in Human Liver Cells
- Identification of Cytosolic Leucyl Aminopeptidase (EC 3.4.11.1) as the Major Cysteinylglycine-Hydrolysing Activity in Rat Liver
- A Novel Influenza A Virus Activating Enzyme from Porcine Lung: Purification and Characterization
- Binding of Urokinase Plasminogen Activator to gp130 via a Putative Urokinase-Binding Consensus Sequence
- Modifications of Glyceraldehyde-3-Phosphate Dehydrogenase Induced by Increasing Concentrations of Peroxynitrite: Early Recognition by 20S Proteasome
- Different Isoforms of the Non-Integrin Laminin Receptor Are Present in Mouse Brain and Bind PrP
- Cell-Type Specific Targeting and Gene Expression Using a Variant of Polyoma VP1 Virus-Like Particles
- Quantitation of Membrane Type Serine Protease 1 (MT-SP1) in Transformed and Normal Cells
- Interaction of Heat Shock Protein 70 Peptide with NK Cells Involves the NK Receptor CD94
- Cystatins C, E/M and F in Human Pleural Fluids of Patients with Neoplastic and Inflammatory Lung Disorders
- A Homodimeric Sporamin-Type Trypsin Inhibitor with Antiproliferative, HIV Reverse Transcriptase-Inhibitory and Antifungal Activities from Wampee (Clausena lansium) Seeds
- Primary Structure and Reactive Site of a Novel Wheat Proteinase Inhibitor of Subtilisin and Chymotrypsin
- Diverse Enzymatic Specificities of Digestive Proteases, 'Intestains', Enable Colorado Potato Beetle Larvae to Counteract the Potato Defence Mechanism
- Protease Inhibitors Prevent Plasminogen-Mediated, But Not Pemphigus Vulgaris-Induced, Acantholysis in Human Epidermis
- Purification and Primary Structure Determination of Human Lysosomal Dipeptidase
- A Bioinformatic Approach to the Identification of Candidate Genes for the Development of New Cancer Diagnostics
