HY5, a positive regulator of light signaling, negatively controls the unfolded protein response inArabidopsis.
Light influences essentially all aspects of plant growth and development. Integration of light signaling with different stress response results in improvement of plant survival rates in ever changing environmental conditions. Diverse environmental stresses affect the protein-folding capacity of the endoplasmic reticulum (ER), thus evoking ER stress in plants. Consequently, the unfolded protein response (UPR), in which a set of molecular chaperones is expressed, is initiated in the ER to alleviate this stress. Although its underlying molecular mechanism remains unknown, light is believed to be required for the ER stress response. In this study, we demonstrate that increasing light intensity elevates the ER stress sensitivity of plants. Moreover, mutation of the ELONGATED HYPOCOTYL 5 (HY5), a key component of light signaling, leads to tolerance to ER stress. This enhanced tolerance ofhy5plants can be attributed to higher expression of UPR genes. HY5 negatively regulates the UPR by competing with basic leucine zipper 28 (bZIP28) to bind to the G-box-like element present in the ER stress response element (ERSE). Furthermore, we found that HY5 undergoes 26S proteasome-mediated degradation under ER stress conditions. Conclusively, we propose a molecular mechanism of crosstalk between the UPR and light signaling, mediated by HY5, which positively mediates light signaling, but negatively regulates UPR gene expression.
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Ganesh M
GM
Nawkar
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Chang Ho
CH
Kang
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Punyakishore
P
Maibam
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Joung Hun
JH
Park
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Young Jun
YJ
Jung
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Ho Byoung
HB
Chae
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Yong Hun
YH
Chi
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
In Jung
IJ
Jung
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Woe Yeon
WY
Kim
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea.
Dae-Jin
DJ
Yun
Division of Applied Life Sciences (BK21) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 52828, Korea sylee@gnu.ac.kr.
Sang Yeol
SY
Lee
D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D050976:Basic-Leucine Zipper Transcription Factors / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000502:physiology*; D059865:Endoplasmic Reticulum Stress / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl; D055537:Light Signal Transduction / Q000502:physiology*; D009154:Mutation; D009687:Nuclear Proteins / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D059748:Proteolysis; D013312:Stress, Physiological; D056811:Unfolded Protein Response / Q000235:genetics*
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
crosstalk; endoplasmic reticulum stress; light signaling; protein-folding capacity; unfolded protein response