The bacterium uses a protein (XptA1) a toxin which helps the nematode to kill and feed on the dead body of the insect. The toxin not only kills the target insect but prevents other predators from eating the body giving free reign to the nematode worms to consume it, multiply and move on. However, until now, researchers had little idea of the make up of XptA1 and thus how it worked. The research team, based at the University of Warwick’s horticultural research arm Warwick HRI, have now been able to reveal the shape of the protein XptA1 and discovered a number of properties that make it a particularly efficient natural insecticide and possible alternative to some commercial insecticides that are facing increased resistance in the insect populations they target.
The researchers at Warwick HRI, together with a team of colleagues with expertise in the Structural Biology group in Biological Sciences and in Chemistry at The University of Warwick, as well as Coventry and Nottingham Universities, found that the protein was formed from four sub units in the shape of a hollow cage or box which is configured to bind well to part of a caterpillar’s gut called "Brush Border Membrane Vesicles" (BBMV).
The XptA1 protein seemed to specifically target the BBMV of caterpillars Pieris Brassicae ?(The cabbage white butterfly caterpillar which are pests for many growers). The hollow box structure appears to be a key element of the protein’s design. The hollow shape allows the protein to act as a receptacle for two other proteins (in the case of XptA1 these are XptB1 and XptC1). This forms a poison "c
Source:University of Warwick