Regulation of Abiotic Stress Signalling by Arabidopsis C-Terminal Domain Phosphatase-Like 1 Requires Interaction with a K-Homology Domain-Containing Protein

• DOI: 10.1371/journal.pone.0080509
• Publication Date: 2013-11-26T23:12:35Z
• Authors: In Sil Jeong; Akihito Fukudome; Emre Aksoy; Woo Young Bang; Sewon Kim; Qingmei Guan; Jeong Dong Bahk; Kimberly A. May; William K. Russell; Jianhua Zhu; Hisashi Koiwa
• Keywords: Bimolecular fluorescence complementation

Arabidopsis thaliana CARBOXYL-TERMINAL DOMAIN (CTD) PHOSPHATASE-LIKE 1 (CPL1) regulates plant transcriptional responses to diverse stress signals. Unlike typical CTD phosphatases, CPL1 contains two double-stranded (ds) RNA binding motifs (dsRBMs) at its C-terminus. Some dsRBMs can bind dsRNA and/or other proteins, but the function of has remained obscure. Here, we report identification REGULATOR OF CBF GENE EXPRESSION 3 (RCF3) as a CPL1-interacting protein. RCF3 co-purified with tandem-affinity-tagged from cultured cells and multiple K-homology (KH) domains, which were predicted be important for single-stranded DNA/RNA. Yeast two-hybrid, luciferase complementation imaging, bimolecular fluorescence analyses established that strongly associate in vivo, an interaction mediated by dsRBM1 KH3/KH4 domains RCF3. Mapping functional regions indicated vivo requires dsRBM1, catalytic activity, nuclear targeting CPL1. Gene expression profiles rcf3 cpl1 mutants similar during iron deficiency, distinct cold response. These results suggest tethering via is part mechanism confers specificity CPL1-mediated regulation.