title: UBC18 mediates ERF1 degradation under light-dark cycles.
abstract: Ethylene Response Factor 1 (ERF1) plays a crucial role in biotic and abiotic stress responses. Previous studies have shown that ERF1 regulates stress-responsive gene expression by binding to different cis-acting elements in response to various stress signals. ERF1 was also reported to be unstable in the dark, and it regulates hypocotyl elongation. Here, we elucidated the mechanism underlying degradation of ERF1. Yeast two-hybrid screening showed that UBIQUITIN-CONJUGATING ENZYME 18 (UBC18) interacted with ERF1. The interaction between ERF1 and UBC18 was verified using pull-down assays and coimmunoprecipitation analyses. We then compared the ERF1 protein abundance in the UBC18 mutant and overexpression plants. Based on the results of protein degradation and in vivo ubiquitination assays, we proposed that UBC18 mediates ERF1 ubiquitination and degradation. ERF1 was more stable in UBC18 mutants and less stable in UBC18 overexpression lines compared with that in wild-type plants. ERF1 was degraded by the 26S proteasome system via regulation of UBC18 and promotes dark-repression of downstream genes and proline accumulation. UBC18 negatively regulated drought and salt stress responses by altering the abundance of ERF1 and the expression of genes downstream of ERF1.
authors: Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei, 10617, Taiwan.
authors: Mei-Chun
authors: MC
authors: Cheng
authors: Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei, 10617, Taiwan.
authors: Wen-Chieh
authors: WC
authors: Kuo
authors: Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei, 10617, Taiwan.
authors: Yi-Ming
authors: YM
authors: Wang
authors: Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei, 10617, Taiwan.
authors: Hsing-Yu
authors: HY
authors: Chen
authors: Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei, 10617, Taiwan.
authors: Tsan-Piao
authors: TP
authors: Lin
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006720:Homozygote; D010454:Peptide Termination Factors / Q000378:metabolism*; D010641:Phenotype; D017440:Photoperiod; D011392:Proline / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D010454:Peptide Termination Factors; C036483:T-DNA; C494978:eukaryotic release factor 1, Arabidopsis; D012965:Sodium Chloride; D011392:Proline; D044763:Ubiquitin-Conjugating Enzymes; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
keywords: E2; Ethylene Response Factor 1 (ERF1); UBIQUITIN-CONJUGATING ENZYME 18 (UBC18); abiotic stress; degradation; proline; ubiquitination