کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1924715 | 1536303 | 2016 | 11 صفحه PDF | دانلود رایگان |
• We gained mechanistic insights into the first Lygus-active β-pore forming protein.
• Protease activation, specific receptor binding and oligomerization are key steps.
• This β-pore forming protein has a mechanistic pathway common to other Bt proteins.
• These mechanistic steps confer novel Lygus insecticidal activity on Cry51Aa2.834_16.
• This suggests that β-pore forming proteins can be insect-specific control agents.
The cotton pests Lygus hesperus and Lygus lineolaris can be controlled by expressing Cry51Aa2.834_16 in cotton. Insecticidal activity of pore-forming proteins is generally associated with damage to the midgut epithelium due to pores, and their biological specificity results from a set of key determinants including proteolytic activation and receptor binding. We conducted mechanistic studies to gain insight into how the first Lygus-active β-pore forming protein variant functions. Biophysical characterization revealed that the full-length Cry51Aa2.834_16 was a stable dimer in solution, and when exposed to Lygus saliva or to trypsin, the protein underwent proteolytic cleavage at the C-terminus of each of the subunits, resulting in dissociation of the dimer to two separate monomers. The monomer showed tight binding to a specific protein in Lygus brush border membranes, and also formed a membrane-associated oligomeric complex both in vitro and in vivo. Chemically cross-linking the β-hairpin to the Cry51Aa2.834_16 body rendered the protein inactive, but still competent to compete for binding sites with the native protein in vivo. Our study suggests that disassociation of the Cry51Aa2.834_16 dimer into monomeric units with unoccupied head-region and sterically unhindered β-hairpin is required for brush border membrane binding, oligomerization, and the subsequent steps leading to insect mortality.
Journal: Archives of Biochemistry and Biophysics - Volume 600, 15 June 2016, Pages 1–11