Abstract
Stem cell number in shoot and floral meristems of Arabidopsis (Arabidopsis thaliana) is regulated by the CLAVATA3 (CLV3) signaling pathway. Perception of the CLV3 peptide requires the receptor kinase CLV1, the receptor-like protein CLV2, and the kinase CORYNE (CRN). Genetic analysis suggested that CLV2 and CRN act together and in parallel with CLV1. We studied the intracellular localization of receptor fusions with fluorescent protein tags and their capacities for interaction via efficiency of fluorescence resonance energy transfer. We found that CLV2 and CRN require each other for export from the endoplasmic reticulum and localization to the plasma membrane (PM). CRN readily forms homomers and interacts with CLV2 through the transmembrane domain and adjacent juxtamembrane sequences. CLV1 forms homomers independently of CLV2 and CRN at the PM. We propose that the CLV3 signal is perceived by a tetrameric CLV2/CRN complex and a CLV1 homodimer that localize to the PM and can interact via CRN.
Highlights
Stem cell number in shoot and floral meristems of Arabidopsis (Arabidopsis thaliana) is regulated by the CLAVATA3 (CLV3) signaling pathway
Via fluorescence resonance energy transfer (FRET), we show that CLV2 and CRN form complexes at the endoplasmic reticulum (ER) that relocalize to the plasma membrane (PM), and we identified the protein domains required for this interaction
We found that constitutive expression of most receptor-GFP fusions from the cauliflower mosaic virus (CaMV) 35S promoter failed to rescue the corresponding mutants in transgenic Arabidopsis
Summary
Stem cell number in shoot and floral meristems of Arabidopsis (Arabidopsis thaliana) is regulated by the CLAVATA3 (CLV3) signaling pathway. Mutations in CLV1 (Clark et al, 1997), encoding a leucine-rich repeat (LRR) receptor kinase, CLV2, encoding a LRR receptor-like protein (Jeong et al, 1999), and CORYNE (CRN), encoding a receptor-like kinase, disrupt CLV3 signaling and allow the stem cell domain to expand (Sablowski, 2007; Muller et al, 2008). Via fluorescence resonance energy transfer (FRET), we show that CLV2 and CRN form complexes at the ER that relocalize to the PM, and we identified the protein domains required for this interaction. We found that CLV1 homomerizes but can interact with CRN and CLV2, suggesting a mechanism for cross talk between the two receptor complexes for CLV3 signaling
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