We are pleased to announce that our paper, “Streptomyces produce a diphtheria toxin-like exotoxin that targets insects” has been published in Nature Microbiology!
In this paper, we describe the discovery of diphtheria toxin homologues in Streptomyces that we named Streptomyces antiquus insecticidal proteins (SAIP). We show that these toxins evolved more than 100 million years ago in a lineage of Streptomyces and have been maintained through vertical transmission under strong stabilizing selection. We determined that SAIP possesses a conserved structure and mechanism as diphtheria toxin. We then show that these proteins are insecticidal and that their receptor is an insect membrane protein called Flower, which is localized to neurons. Accordingly, we demonstrate the SAIP targets Flower leading to insect paralysis, immunosuppression, and death. Finally, we show that these Streptomyces produce unique secondary metabolites when they colonize and consume the carcasses of the killed insects. This work is the first demonstration of an exotoxin in Streptomyces and suggests that these bacteria could be cryptic insect pathogens.
This work stemmed from a long-term collaboration between our lab, Ying Xu, Min Don, Cameron Currie, and others. So happy to see this paper finally published!
Read more about the paper here.