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

Content Provider	Semantic Scholar
Author	Chen, Jiang Hua, Gang Jurat-Fuentes, Juan Luis Abdullah, Mohd Amir F. Adang, Michael J.
Copyright Year	2007
Abstract	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 (1)H-NMR spectroscopy confirmed that our purified CR12-MPED peptide mainly consisted of beta-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 (1 microM)-affinity sites. CR12-MPED-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.
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://web.utk.edu/~jurat/PDF%20files/Chen_Bt%20synergism%20with%20cad_PNAS_2007.pdf
PubMed reference number	17724346v1
Volume Number	104
Issue Number	35
Journal	Proceedings of the National Academy of Sciences of the United States of America
Language	English
Access Restriction	Open
Subject Keyword	Adverse reaction to drug Affinity Avian crop Bacillus thuringiensis Biopesticides Brush Border Cadherins Circular Dichroism Larva Microvilli Midgut Plasma membrane Spectroscopy, Nuclear Magnetic Resonance Toxin Vesicle (morphologic abnormality) viral capsid secondary envelopment
Content Type	Text
Resource Type	Article