X-ray imaging reveals insights into a natural compound that kills mosquitoes
Investigating a mosquito toxin produced by bacteria could lead to safer and more effective anti-mosquito products.
Many of the chemicals used to deter or eliminate disease-causing mosquitoes can pollute ecosystems and fuel the development of even more problematic, insecticide-resistant species – but luckily, we may soon have better options.
Scientists previously discovered that a strain of naturally occurring bacteria called Bacillus thuringiensis israelensis (Bti) produces several compounds that kill mosquito larvae but are harmless to most other organisms. These compounds exist in crystal form within the bacteria, and when the microbes are eaten by a larva, the high pH and digestive enzymes in their intestines cause the crystals to dissolve and rearrange into molecules that perforate the larva’s intestinal cell membranes and that Kill insect quickly.
New research from the University of Grenoble Alpes, published March 2, 2020 in Nature Communications, has revealed the atomic structure of the strongest Bti crystal and explained the mechanism by which the transformed toxin cuts through mosquito cell membranes.
“These results help explain differences in toxicity, even if an individual is changed atom. This opens the door to the rational design of safe and effective toxins to control specific mosquito species or disease targets, ”said Nicholas Sauter, senior scientist in the Department of Molecular Biophysics and Integrated Bioimaging (MBIB) at Berkeley Lab and one of the article authors.
Sauter and two other MBIB co-authors used their computer skills to process the structural data collected using the method of X-ray crystallography performed on the linear coherent light source (LCLS) at the SLAC National Accelerator Laboratory. “X-ray laser light sources like the LCLS are the only technology that can produce rays that are focused enough to examine the tiny Bti crystals,” added Sauter. “Collecting and then interpreting this complex data involved researchers from 10 institutions – a great example of ‘great scientific’ collaboration.”
Reference: “Serial femtosecond crystallography on crystals grown in vivo drives the elucidation of the mosquito-causing Cyt1Aa bioactivation cascade” by Guillaume Tetreau, Anne-Sophie Banneville, Elena A. Andreeva, Aaron S. Brewster, Mark S. Hunter, Raymond G. Sierra, Jean – Marie Teulon, Iris D. Young, Niamh Burke, Tilman A. Grünewald, Joël Beaudouin, Irina Snigireva, Maria Teresa Fernandez-Luna, Alister Burt, Hyun-Woo-Park, Luca Signor, Jayesh A. Bafna, Rabia Sadir, Daphna Fenel Elisabetta Boeri-Erba, Maria Bacia, Ninon Zala, Frédéric Laporte, Laurence Després, Martin Weik, Sébastien Boutet, Martin Rosenthal, Nicolas Coquelle, Manfred Burghammer, Duilio Cascio, Michael R. Sawaya, Mathias Winterhalter, Enrico Gratton, Irina Gutsche Brian Federici, Jean-Luc Pellequer, Nicholas K. Sauter and Jacques-Philippe Colletier, March 2, 2020, Nature Communications.
DOI: 10.1038 / s41467-020-14894-w