title: Sumoylation stabilizes RACK1B and enhance its interaction with RAP2.6 in the abscisic acid response.
abstract: The highly conserved eukaryotic WD40 repeat protein, Receptor for Activated C Kinase 1 (RACK1), is involved in the abscisic acid (ABA) response in Arabidopsis. However, the regulation of RACK1 and the proteins with which it interacts are poorly understood. Here, we show that RACK1B is sumoylated at four residues, Lys50, Lys276, Lys281 and Lys291. Sumoylation increases RACK1B stability and its tolerance to ubiquitination-mediated degradation in ABA response. As a result, sumoylation leads to enhanced interaction between RACK1B and RAP2.6, an AP2/ERF family transcription factor. RACK1B binds directly to the AP2 domain of RAP2.6, which alters the affinity of RAP2.6 for CE1 and GCC cis-acting regulatory elements. Taken together, our findings illustrate that protein stability controlled by dynamic post-transcriptional modification is a critical regulatory mechanism for RACK1B, which functions as scaffold protein for RAP2.6 in ABA signaling.
authors.affiliation: Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.|University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Rongkai
authors.initials: R
authors.lastname: Guo
authors.affiliation: Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Weining
authors.initials: W
authors.lastname: Sun
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D030821:Plants, Genetically Modified; D055550:Protein Stability; D000075370:Receptors for Activated C Kinase / Q000378:metabolism*; D015398:Signal Transduction; D058207:Sumoylation; D014157:Transcription Factors / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; C515163:RACK1 protein, Arabidopsis; C000629139:RACK1B protein, Arabidopsis; C549102:RAP2.6 protein, Arabidopsis; D000075370:Receptors for Activated C Kinase; D014157:Transcription Factors; D000040:Abscisic Acid