Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Bacillus thuringiensis subsp. israelensis Cyt1Aa Synergizes Cry11Aa Toxin by Functioning as a Membrane-Bound Receptor

Claudia Pérez, Luisa E. Fernandez, Jianguang Sun, Jorge Luis Folch, Sarjeet S. Gill, Mario Soberón, Alejandra Bravo and John H. Law
Proceedings of the National Academy of Sciences of the United States of America
Vol. 102, No. 51, Enzymatic Rescue of Myelination (Dec. 20, 2005), pp. 18303-18308
Stable URL: http://www.jstor.org/stable/4152612
Page Count: 6
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Bacillus thuringiensis subsp. israelensis Cyt1Aa Synergizes Cry11Aa Toxin
              by Functioning as a Membrane-Bound Receptor
Preview not available

Abstract

Bacillus thuringiensis subsp. israelensis produces crystal proteins. Cry (4Aa, 4Ba, 10Aa, and 11Aa) and Cyt (1Aa and 2Ba) proteins, toxic to mosquito vectors of human diseases. Cyt1Aa overcomes insect resistance to Cry11Aa and Cry4 toxins and synergizes the toxicity of these toxins. However, the molecular mechanism of synergism remains unsolved. Here, we provide evidence that Cyt1Aa functions as a receptor of Cry11Aa. Sequential-binding analysis of Cyt1Aa and Cry11Aa revealed that Cyt1Aa binding to Aedes aegypti brush border membrane vesicles enhanced the binding of biotinylated-Cry11Aa. The Cyt1Aa- and Cry11Aa-binding epitopes were mapped by means of the yeast two-hybrid system, peptide arrays, and heterologous competition assays with synthetic peptides. Two exposed regions in Cyt1Aa, loop β6-αE and part of β7, bind Cry11Aa. On the other side, Cry11Aa binds Cyt1Aa proteins by means of domain II-loop α8 and β-4, which are also involved in midgut receptor interaction. Characterization of single-point mutations in Cry11Aa and Cyt1Aa revealed key Cry11Aa (S259 and E266) and Cyt1Aa (K198, E204 and K225) residues involved in the interaction of both proteins and in synergism. Additionally, a Cyt1Aa loop β6-αE mutant (K198A) with enhanced synergism to Cry11Aa was isolated. Data provided here strongly indicates that Cyt1Aa synergizes or suppresses resistance to Cry11Aa toxin by functioning as a membrane-bound receptor. Bacillus thuringiensis subsp. israelensis is a highly effective pathogenic bacterium because it produces a toxin and also its functional receptor, promoting toxin binding to the target membrane and causing toxicity.

Page Thumbnails

  • Thumbnail: Page 
[18303]
    [18303]
  • Thumbnail: Page 
18304
    18304
  • Thumbnail: Page 
18305
    18305
  • Thumbnail: Page 
18306
    18306
  • Thumbnail: Page 
18307
    18307
  • Thumbnail: Page 
18308
    18308