| Title: | Positive selection of digestive Cys proteases in herbivorous Coleoptera |
| Author(s): | Vorster J; Rasoolizadeh A; Goulet MC; Cloutier C; Sainsbury F; Michaud D; |
| Address: | "Departement de phytologie, CRIV-Biotechnologie, Universite Laval, Quebec, QC G1V 0A6, Canada; Department of Plant and Soil Science, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa. Departement de phytologie, CRIV-Biotechnologie, Universite Laval, Quebec, QC G1V 0A6, Canada. Departement de biologie, Universite Laval, Quebec, QC G1V 0A6, Canada. Departement de phytologie, CRIV-Biotechnologie, Universite Laval, Quebec, QC G1V 0A6, Canada; The University of Queensland, Australian Institute for Bioengineering and Nanotechnology, Centre for Biomolecular Engineering, St. Lucia, Queensland 4072, Australia. Departement de phytologie, CRIV-Biotechnologie, Universite Laval, Quebec, QC G1V 0A6, Canada. Electronic address: dominique.michaud@fsaa.ulaval.ca" |
| DOI: | 10.1016/j.ibmb.2015.07.017 |
| ISSN/ISBN: | 1879-0240 (Electronic) 0965-1748 (Linking) |
| Abstract: | "Positive selection is thought to contribute to the functional diversification of insect-inducible protease inhibitors in plants in response to selective pressures exerted by the digestive proteases of their herbivorous enemies. Here we assessed whether a reciprocal evolutionary process takes place on the insect side, and whether ingestion of a positively selected plant inhibitor may translate into a measurable rebalancing of midgut proteases in vivo. Midgut Cys proteases of herbivorous Coleoptera, including the major pest Colorado potato beetle (Leptinotarsa decemlineata), were first compared using a codon-based evolutionary model to look for the occurrence of hypervariable, positively selected amino acid sites among the tested sequences. Hypervariable sites were found, distributed within -or close to- amino acid regions interacting with Cys-type inhibitors of the plant cystatin protein family. A close examination of L. decemlineata sequences indicated a link between their assignment to protease functional families and amino acid identity at positively selected sites. A function-diversifying role for positive selection was further suggested empirically by in vitro protease assays and a shotgun proteomic analysis of L. decemlineata Cys proteases showing a differential rebalancing of protease functional family complements in larvae fed single variants of a model cystatin mutated at positively selected amino acid sites. These data confirm overall the occurrence of hypervariable, positively selected amino acid sites in herbivorous Coleoptera digestive Cys proteases. They also support the idea of an adaptive role for positive selection, useful to generate functionally diverse proteases in insect herbivores ingesting functionally diverse, rapidly evolving dietary cystatins" |
| Keywords: | Amino Acid Sequence Animals Biological Evolution Coleoptera/*enzymology/genetics Cystatins/metabolism Digestive System/enzymology Herbivory Larva/enzymology/genetics Peptide Hydrolases/genetics/*metabolism Plant Proteins/genetics/*metabolism Proteomics Se; |
| Notes: | "MedlineVorster, Juan Rasoolizadeh, Asieh Goulet, Marie-Claire Cloutier, Conrad Sainsbury, Frank Michaud, Dominique eng Research Support, Non-U.S. Gov't England 2015/08/13 Insect Biochem Mol Biol. 2015 Oct; 65:10-9. doi: 10.1016/j.ibmb.2015.07.017. Epub 2015 Aug 8" |
