5iyx | pdb_00005iyx
Crystal structure of the Arabidopsis receptor kinase HAESA in complex with the peptide hormone IDA and the co-receptor SERK1
Structural highlights
Function[RLK5_ARATH] Receptor with a dual specificity kinase activity acting on both serine/threonine- and tyrosine-containing substrates that controls floral organ abscission. May interact with the 'INFLORESCENCE DEFICIENT IN ABSCISSION' (IDA) ligands family.[1] [2] [3] [SERK1_ARATH] Dual specificity kinase acting on both serine/threonine- and tyrosine-containing substrates. Phosphorylates BRI1 on 'Ser-887' and CDC48 on at least one threonine residue and on 'Ser-41'. Confers embryogenic competence. Acts redundantly with SERK2 as a control point for sporophytic development controlling male gametophyte production. Involved in the brassinolide signaling pathway.[4] [5] [IDA_ARATH] Involved in an ethylene-independent separation step of floral abscission. May act with RLK5 and HSL2 as ligand-receptor pairs.[6] Publication Abstract from PubMedPlants constantly renew during their life cycle and thus require to shed senescent and damaged organs. Floral abscission is controlled by the leucine-rich repeat receptor kinase (LRR-RK) HAESA and the peptide hormone IDA. It is unknown how expression of IDA in the abscission zone leads to HAESA activation. Here we show that IDA is sensed directly by the HAESA ectodomain. Crystal structures of HAESA in complex with IDA reveal a hormone binding pocket that accommodates an active dodecamer peptide. A central hydroxyproline residue anchors IDA to the receptor. The HAESA co-receptor SERK1, a positive regulator of the floral abscission pathway, allows for high-affinity sensing of the peptide hormone by binding to an Arg-His-Asn motif in IDA. This sequence pattern is conserved among diverse plant peptides, suggesting that plant peptide hormone receptors may share a common ligand binding mode and activation mechanism. Mechanistic insight into a peptide hormone signaling complex mediating floral organ abscission.,Santiago J, Brandt B, Wildhagen M, Hohmann U, Hothorn LA, Butenko MA, Hothorn M Elife. 2016 Apr 8;5. pii: e15075. doi: 10.7554/eLife.15075. PMID:27058169[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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