Structural analysis of HTL and D14 proteins reveals the basis for ligand selectivity in Striga (Nature Comm.)

Strigolactones induce germination of parasitic plant Striga, which causes more crop loss in Africa than any other parasite. Karrakins are structurally related to strigolactones, yet they do not induce Striga germination. By studying the structure and substrate recognition of strigolactone and karrakin-binding proteins in Striga hermonthica, Zu et al. gained insight in high sensitivity of Striga to wide variety of strigolactones. The parasite specific clade of HYPOSENSITIVE TO LIGHT (HTL) bound to wide variety of strigolactones but not to karrakin. Compound binding pocket was larger in the pathogen specific HTLs, allowing for HTL to bind at low concentrations and recognize wide variety of hosts. The importance of pocket size for ligand recognition was verified using specific mutations. This study improves our understanding of strigolactone receptor evolution and provides new resources for the future methods to combat Striga. (Summary by Magdalena Julkowska) Nat. Commun. 10.1038/s41467-018-06452-2