New family of venom peptides discovered

Female emerald jewel wasps of the species Ampulex compressa inject venom into the brains of cockroaches to subdue them so they can serve as edible hosts for wasp eggs and larvae. The venom is a complex mixture of proteins, peptides, and small molecules. By analyzing wasp venom with mass spectrometry, Michael E. Adams and coworkers at the University of California, Riverside, found that the venom contains a previously unknown family of peptides, which the researchers dub “ampulexins” (Biochemistry 2018, DOI: 10.1021/acs.biochem.7b00916). The wasp’s venom apparatus consists of a venom gland and a venom sac, both of which produce ampulexins. The two structures have distinct peptide and protein profiles, with milked venom more closely resembling that of the venom sac. The researchers tried to determine the ampulexins’ function and found that they are neither antimicrobial nor cytotoxic. When they injected one of the peptides, ampulexin-1, into cockroaches, the insects withstood higher electric voltages without trying to escape. Although the effect lasted for less time than it does when wasps sting cockroaches, the findings suggest that the peptides play a role in the early stage of subduing the cockroaches. Adams’s lab is now working to identify ampulexins’ cellular and molecular targets in the nervous system and to comprehensively analyze gene and protein expression in the wasp venom.