Toxins of the venom of tarantulas (Theraphosidae, Arachnida) in interspecies interactions

Spiders are the most important entomophages in ecosystems. They are the most numerous poisonous animals on the planet, indispensable regulators of populations’ numbers by killing mainly insects and other small arthropods. Spiders are an integral part of the food chain; they produce venom serving to immobilize the prey. Spider venoms are a “natural combinatorial library” of biologically active substances, with varying effectiveness and specificity. A feature of the biological effect of spider’s venom is a unique combination of the low toxicity of the whole venom, for both animals and humans, with high selectivity of the interaction of the neurotoxins, which are part of the venom, with the molecular structures of ion channels and synaptic receptors of the nervous system. The present review introduces the reader to new fundamental facts, ideas and perspective of the practical application of spider’s venoms in biomedical research and drug design. The current state of research on a unique set of polypeptide toxins which serve as chemical factors (allomons) of the interspecific (allelochemical) interactions of spiders of the family Thetaphosidae is considered. Modern information on the structure of spiders’ venom toxins is analyzed using the UniProt database. The latest bioecological and toxicological characteristics of tarantulas are presented. The chemical nature and mechanism of action of some unique toxins selectively acting on key processes in the nervous system are considered. The toxins act upon synaptic transmission and the functioning ion channels, which allow spiders not only to interact with various molecular targets of the prey or predator, but also to implement various life strategies, gaining an evolutionary advantage.