title: Identification of critical functional residues of receptor-like kinase ERECTA.
abstract: In plants, extracellular signals are primarily sensed by plasma membrane-localized receptor-like kinases (RLKs). ERECTA is a leucine-rich repeat RLK that together with its paralogs ERECTA-like 1 (ERL1) and ERL2 regulates multiple aspects of plant development. ERECTA forms complexes with a range of co-receptors and senses secreted cysteine-rich small proteins from the EPF/EPFL family. Currently the mechanism of the cytoplasmic domain activation and transmission of the signal by ERECTA is unclear. To gain a better understanding we performed a structure-function analysis by introducing altered ERECTA genes into erecta and erecta erl1 erl2 mutants. These experiments indicated that ERECTA's ability to phosphorylate is functionally significant, and that while the cytoplasmic juxtamembrane domain is important for ERECTA function, the C-terminal tail is not. An analysis of multiple putative phosphorylation sites identified four amino acids in the activation segment of the kinase domain as functionally important. Homology of those residues to functionally significant amino acids in multiple other plant RLKs emphasizes similarities in RLK function. Specifically, our data predicts Thr812 as a primary site of phosphor-activation and potential inhibitory phosphorylation of Tyr815 and Tyr820. In addition, our experiments suggest that there are differences in the molecular mechanism of ERECTA function during regulation of stomata development and in elongation of above-ground organs.
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Pawel Z
authors.initials: PZ
authors.lastname: Kosentka
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Yonas A
authors.initials: YA
authors.lastname: Simon
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Binita
authors.initials: B
authors.lastname: Satpathy
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Maradiaga
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Omar
authors.initials: O
authors.lastname: Mitoubsi
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Elena D
authors.initials: ED
authors.lastname: Shpak
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D017343:Genes, Plant / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D011956:Receptors, Cell Surface; C457763:ER protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: Activation segment; ERECTA; LRR-RLK; kinase domain; phosphorylation; receptor kinase; signal transduction; site-directed mutagenesis; structure–functional analysis