PT  - JOURNAL ARTICLE
AU  - Satohiro Okuda
AU  - Satoshi Fujita
AU  - Andrea Moretti
AU  - Ulrich Hohmann
AU  - Verónica G. Doblas
AU  - Yan Ma
AU  - Alexandre Pfister
AU  - Benjamin Brandt
AU  - Niko Geldner
AU  - Michael Hothorn
TI  - Molecular mechanism for the recognition of sequence-divergent CIF peptides by the plant receptor kinases GSO1/SGN3 and GSO2
AID  - 10.1101/692228
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 692228
4099  - http://biorxiv.org/content/early/2019/07/05/692228.short
4100  - http://biorxiv.org/content/early/2019/07/05/692228.full
AB  - Plants use leucine-rich repeat receptor kinases (LRR-RKs) to sense sequence diverse peptide hormones at the cell surface. A 3.0 Å crystal structure of the LRR-RK GSO1/SGN3 regulating Casparian strip formation in the endodermis reveals a large spiral-shaped ectodomain. The domain provides a binding platform for 21 amino-acid CIF peptide ligands, which are tyrosine sulfated by the tyrosylprotein sulfotransferase TPST/SGN2. GSO1/SGN3 harbors a binding pocket for sulfotyrosine and makes extended backbone interactions with CIF2. Quantitative biochemical comparisons reveal that GSO1/SGN3 – CIF2 represents one of the strongest receptor-ligand pairs known in plants. Multiple missense mutations are required to block CIF2 binding in vitro, and GSO1/SGN3 function in vivo. Using structure-guided sequence analysis we uncover novel CIF peptides conserved among higher plants. Quantitative binding assays with known and novel CIFs suggest that the homologous LRR-RKs GSO1/SGN3 and GSO2 have evolved unique peptide binding properties to control different developmental processes. A quantitative biochemical interaction screen, a CIF peptide antagonist and genetic analyses together implicate SERK LRR-RKs as essential co-receptor kinases required for GSO1/SGN3 and GSO2 receptor activation. 0ur work provides a mechanistic framework for the recognition of sequence-divergent peptide hormones in plants.Significance Statement Two sequence-related plant membrane receptor kinases and their shape-complementary co-receptors are shown to selectively sense members of a small family of secreted peptide hormones to control formation of an important diffusion barrier in the plant root.