Molecular insights into mechanisms of lepidopteran serine proteinase resistance to natural plant defenses

Plants have a wide range of chemical defenses against predation, including substances that target digestive serine proteinases of herbivorous. Previous works demonstrated that lepidopteran insects have digestive serine proteinases resistant to plant proteinase inhibitors (PPIs) and ketone modificati...

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Published in:Biochemical and biophysical research communications Vol. 467; no. 4; pp. 885 - 891
Main Authors: Tamaki, Fábio K., Terra, Walter R.
Format: Journal Article
Language:English
Published: United States Elsevier Inc 27-11-2015
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Summary:Plants have a wide range of chemical defenses against predation, including substances that target digestive serine proteinases of herbivorous. Previous works demonstrated that lepidopteran insects have digestive serine proteinases resistant to plant proteinase inhibitors (PPIs) and ketone modifications, while coleopteran ones are sensitive to those plant defenses. This paper focuses on molecular aspects that lead lepidopteran serine proteinases to PPI and ketone modification resistance. Using biochemical experiments and computer 3D modeling we demonstrated that lepidopteran trypsins are more hydrophobic than coleopteran ones, a feature associated to trypsin oligomerization and decreased inhibition by PPI. Moreover, the determination of pKa values of chymotrypsin catalytic residues obtained by TPCK modification indicates that the environment around the active site of ketone-resistant and –sensitive chymotrypsins are different. Structural analysis using resistant and sensitive chymotrypsins data allowed us to point 2 hotspot regions around the active site that could explain the observed differences. Our set of results highlights features of serine proteinases important for understanding the resistance of insects to plant chemical defenses. [Display omitted] •Lepidopteran trypsins are more hydrophobic than coleopteran ones.•Trypsin hydrophobicity-associated oligomerization seems to avoid plant inhibitors.•Lepidopteran chymotrypsins have catalytic residues with high pKa.•High pKa of catalytic residues are associated with ketone resistance.•Structural features explain changes in properties of chymotrypsin catalytic residues.
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ISSN:0006-291X
1090-2104
DOI:10.1016/j.bbrc.2015.10.049