Single substitutions to closely related amino acids contribute to the functional diversification of an insect-inducible, positively selected plant cystatin
| Autor: | Asieh Rasoolizadeh, Frank Sainsbury, Conrad Cloutier, Dominique Michaud, Marie-Claire Goulet |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Proteases Insecta medicine.medical_treatment Molecular Sequence Data Cysteine Proteinase Inhibitors Biology Biochemistry Host-Parasite Interactions 03 medical and health sciences Valine medicine Animals Amino Acid Sequence Amino Acids Molecular Biology Peptide sequence Plant Proteins Genetics chemistry.chemical_classification Protease Molecular Structure Sequence Homology Amino Acid Protein primary structure Genetic Variation Cell Biology Plants Cystatins Amino acid Coleoptera Plant Leaves 030104 developmental biology Amino Acid Substitution chemistry Larva Mutagenesis Site-Directed Cystatin Leucine |
| Zdroj: | The FEBS Journal. 283:1323-1335 |
| ISSN: | 1742-464X |
| Popis: | A causal link has been reported between positively selected amino acids in plant cystatins and the inhibitory range of these proteins against insect digestive cysteine (Cys) proteases. Here we assessed the impact of single substitutions to closely related amino acids on the contribution of positive selection to cystatin diversification. Cystatin sequence alignments, while confirming hypervariability, indicated a preference for related amino acids at positively selected sites. For example, the non-polar residues leucine (Leu), isoleucine (Ile) and valine (Val) were shown to predominate at positively selected site 2 in the N-terminal region, unlike selected sites 6 and 10, where polar residues are preferred. The model cystatin SlCYS8 and single variants with Leu, Ile or Val at position 2 were compared with regard to their ability to bind digestive proteases of the coleopteran pest Leptinotarsa decemlineata and to induce compensatory responses in this insect. A functional proteomics procedure to capture target Cys proteases in midgut extracts allowed confirmation of distinct binding profiles for the cystatin variants. A shotgun proteomics procedure to monitor whole Cys protease complements revealed protease family specific compensatory responses in the insect, dependent on the variant ingested. Our data confirm the contribution of closely related amino acids to the functional diversity of positively selected plant cystatins in a broader structure/function context imposing physicochemical constraints to primary structure alterations. They also underline the complexity of protease/inhibitor interactions in plant-insect systems, and the challenges still to be met in order to harness the full potential of ectopically expressed protease inhibitors in crop protection. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
| Nepřihlášeným uživatelům se plný text nezobrazuje | K zobrazení výsledku je třeba se přihlásit. |