Insect pests can have a negative impact on agriculture and besides, the pesticides used to control these pests end up turning into an inefficient procedure due to resistance developed.  The discovery and characterization of a new fungal toxin, the anisoplin, has been quite important since it enables the design of new environmental sustainability strategy in order to fight against these organisms that cause severe damages in crops and can provoke huge economic losses and environmental damage.

This finding was possible thank to the collaboration between two research groups of Universidad Politécnica de Madrid (UPM) and Universidad Complutense within International Programme for Attracting Talent (PICATA, Campus Moncloa: Campus of International Excellence UPM-UCM).

The anisoplin is a toxic protein that belongs to the fungal ribotoxins group, a protein family that can be lethal. However they come from common fungus and are apparently inoffensive such as the Aspergillus and Penicillium species. They are so harmless that some of these funguses are used for food processing such as tofu or even medicines such as penicillin. These ribotoxins are enzymes.

In this way, proteins can act as efficient catalysts and selective of very specific chemical reactions. In this case, these proteins are enzymes of a family known as ribonucleasas because they degrade ribonucleic acid (RNA). However, the ribotoxins are special ribonucleases because they only break one RNA bond of the thousands found in the cell, and thus they kill the cells by nullifying their ability to produce proteins.

The ribotoxins have a great insecticidal capacity and have proved to be especially efficient against cells and insect larvae. For this reason, this finding has acquired a particular relevance since the fungus that produces anisoplin is a known entomopathogen, that is, its natural function is to infect and kill insects. And what is more, Metarhizium anisopliae has been used to control pests since the late nineteenth century.

Researchers have recently found that the ribotoxins are efficient for the control of bee mites (Varroa destructor) and at least for one of the mosquitoes responsible for the transmission of malaria (Anopheles gambiae).

The anisoplin finding is the result of a collaborative research between the group of Integrated pest management from UPM, focused on the study and development of methods of pest control, and the group of Toxic proteins from UCM, with an extend experience in the structural and functional characterization of proteins.

Pilar Medina, one of the two researchers participating in the study, says “the finding of the anisoplin opens the door to the design of new molecular strategies, not only for the pest control of crops, but also for the potential prevention of diseases as serious as malaria”. However, she also adds “there is still a lot of work to do. We expect to have the resources needed for it”.

M. Olombrada, P. Medina, F. Budia, J.G. Gavilanes, A. Martínez-del-Pozo y L. García-Ortega (2017) Characterization of a new toxin from the entomopathogenic fungus Metarhizium anisopliae: the ribotoxin anisoplin Biological Chemistry 398, 135-142.

M. Olombrada, A. Martínez-del-Pozo, P. Medina, F. Budia, J.G. Gavilanes y L. García-Ortega (2014) Fungal ribotoxins: natural protein-based weapons against insects Toxicon 83, 69-74.