Evidence for intermolecular interactions between the intracellular domains of the arabidopsis receptor-like kinase ACR4, its homologs and the Wox5 transcription factor

• Published in: PloS one 2015-03, Vol.10 (3), p.e0118861-e0118861
• Main Authors: Meyer, Matthew R, Shah, Shweta, Zhang, J, Rohrs, Henry, Rao, A Gururaj
• Format: Article
• Language: English
• Subjects: Analysis; Arabidopsis; Arabidopsis - chemistry; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Binding Sites; Biochemistry; Biophysics; Cell differentiation; Cloning; Conserved sequence; Dihydrodipicolinate Reductase - chemistry; Dihydrodipicolinate Reductase - metabolism; Genomes; Homeodomain Proteins - chemistry; Homeodomain Proteins - metabolism; Homology; Influence; Intracellular; Kinases; Ligands; Mass spectrometry; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Models, Molecular; Molecular biology; Nucleotide sequence; Peptides; Phosphorylation; Physiological aspects; Protein Binding; Protein interaction; Protein Structure, Secondary; Protein Structure, Tertiary; Protein-protein interactions; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - metabolism; Proteins; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; Scientific imaging; Signal transduction; Signaling; Stem cells; Transcription factors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0118861

Arabidopsis CRINKLY4 (ACR4) is a receptor-like kinase (RLK) involved in the global development of the plant. The Arabidopsis genome encodes four homologs of ACR4 that contain sequence similarity and analogous architectural elements to ACR4, termed Arabidopsis CRINKLY4 Related (AtCRRs) proteins. Additionally, a signaling module has been previously proposed including a postulated peptide ligand, CLE40, the ACR4 RLK, and the WOX5 transcription factor that engage in a possible feedback mechanism controlling stem cell differentiation. However, little biochemical evidence is available to ascertain the molecular aspects of receptor heterodimerization and the role of phosphorylation in these interactions. Therefore, we have undertaken an investigation of the in vitro interactions between the intracellular domains (ICD) of ACR4, the CRRs and WOX5. We demonstrate that interaction can occur between ACR4 and all four CRRs in the unphosphorylated state. However, phosphorylation dependency is observed for the interaction between ACR4 and CRR3. Furthermore, sequence analysis of the ACR4 gene family has revealed a conserved 'KDSAF' motif that may be involved in protein-protein interactions among the receptor family. We demonstrate that peptides harboring this conserved motif in CRR3 and CRK1are able to bind to the ACR4 kinase domain. Our investigations also indicate that the ACR4 ICD can interact with and phosphorylate the transcription factor WOX5.