Recognition of sequence-divergent CIF peptides by the plant receptor kinases GSO1/SGN3 and GSO2 (bioRxiv)

SCHENGEN 3 [SGN3, also known as GASSHO1 (GSO1)] is a leucine-rich repeat receptor kinase (LRR-RK) previously shown to interact with CIF peptides (CASPARIAN STRIP INTEGRITY FACTORS) to regulate the development of the Casparian strip boundary in roots. Here, Okuda et al. characterize the CIF/LRR-RK interaction. They show that that there is a wide range of binding affinities of LRR-RK / peptide ligand interactions and that GSO1/SGN3 forms the strongest receptor-ligand interactions identified in plantshas  and has a longer LRR domain and peptide binding domain than other LRR-RKs. Mutational studies indicate that this strong interaction is mediated by a large number of residues., and that multiple mutations are required to disrupt it. Additionally, the authors identified two previously unannotated CIF proteins and implicate SERK LRR-RKs as essential co-receptor kinases. (Summary by Mary Williams) bioRxiv 10.1101/692228