Synergism of Bacillus thuringiensis toxins by a fragment of a toxin-binding cadherin

被引:94
作者
Chen, Jiang
Hua, Gang
Jurat-Fuentes, Juan Luis
Abdullah, Mohd Amir
Adang, Michael J. [1 ]
机构
[1] Univ Georgia, Dept Entomol, Athens, GA 30602 USA
[2] Univ Georgia, Dept Biochem & Mol Biol, Athens, GA 30602 USA
关键词
cry insecticidal protein; synergist;
D O I
10.1073/pnas.0706011104
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The insecticidal crystal proteins produced by Bacillus thuringiensis (Bt) are broadly used to control insect pests with agricultural importance. The cadherin Bt-R-1 is a binding protein for Bt Cry1A toxins in midgut epithelia of tobacco hornworm (Manduca sexta). We previously identified the Bt-R-1 region most proximal to the cell membrane (CR12-MPED) as the essential binding region required for Cry1Ab-mediated cytotoxicity. Here, we report that a peptide containing this region expressed in Escherichia coli functions as a synergist of Cry1A toxicity against lepidopteran larvae. Far-UV circular dichroism and H-1-NMR spectroscopy confirmed that our purified CR12-MPED peptide mainly consisted of P-strands and random coils with unfolded structure. CR12-MPED peptide bound brush border membrane vesicles with high affinity (K-d = 32 nM) and insect midgut microvilli but did not alter Cry1Ab or Cry1Ac binding localization in the midgut. By BIAcore analysis we demonstrate that Cry1Ab binds CR12-MPED at high (9 nM)- and low (11 mu M)-affinity sites. CR12-IMPIED-mediated Cry1A toxicity enhancement was significantly reduced when the high-affinity Cry1A-binding epitope ((1416)GVLTLNIQ(1423)) within the peptide was altered. Because the mixtures of low Bt toxin dose and CR12-MPED peptide effectively control target insect pests, our discovery has important implications related to the use of this peptide to enhance insecticidal activity of Bt toxin-based biopesticides and transgenic Bt crops.
引用
收藏
页码:13901 / 13906
页数:6
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