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bioRxiv · 10.1101/2020.08.10.245050

Crystal structures of Arabidopsis and Physcomitrella CR4 reveal the molecular architecture of CRINKLY4 receptor kinases.

Okuda, S.·Hothorn, L. A.·Hothorn, M.
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Abstract

Plant-unique receptor kinases harbor conserved cytoplasmic kinase domains and sequence-diverse ectodomains. Here we report crystal structures of CRINKLY4-type ectodomains from Arabidopsis ACR4 and Physcomitrella patens PpCR4 at 1.95 [A] and 2.70 [A] resolution, respectively. Monomeric CRINKLY4 ectodomains harbor a N-terminal WD40 domain and a cysteine-rich domain (CRD) connected by a short linker. The WD40 domain forms a seven-bladed {beta}-propeller with the N-terminal strand buried in its center. Each propeller blade is stabilized by a disulfide bond and contributes to the formation of a putative ligand binding groove. The CRD forms a {beta}-sandwich structure stabilized by six disulfide bonds and shares low structural homology with tumor necrosis factor receptor domains. Quantitative binding assays reveal that ACR4 is not a direct receptor for the peptide hormone CLE40. An ACR4 variant lacking the entire CRD can rescue the known acr4-2 mutant phenotype, as can expression of PpCR4. Together, an evolutionary conserved signaling function for CRINKLY4 receptor kinases is encoded in its WD40 domain.

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Okuda, S., Hothorn, L. A., Hothorn, M.. 2020-08-10. Crystal structures of Arabidopsis and Physcomitrella CR4 reveal the molecular architecture of CRINKLY4 receptor kinases.. https://doi.org/10.1101/2020.08.10.245050

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