Skip to main content
ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Plant, Soil and Nutrition Research » Research » Publications at this Location » Publication #322367

Title: UV-damaged DNA binding protein-1 and de-etiolated-1 regulate golden 2-like transcription factor by assembling a cullin 4-based ubiquitin ligase in tomato

item TANG, XIAOFENG - Sichuan University
item MIAO, MIN - Sichuan University
item NIU, XIANGLI - Sichuan University
item ZHANG, DEFANG - Sichuan University
item CAO, XULV - Sichuan University
item WANG, ANQUAN - Boyce Thompson Institute
item Giovannoni, James
item LIU, YONGSHENG - Sichuan University

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2015
Publication Date: 9/9/2015
Citation: Tang, X., Miao, M., Niu, X., Zhang, D., Cao, X., Wang, A., Giovannoni, J.J., Liu, Y. 2015. UV-damaged DNA binding protein-1 and de-etiolated-1 regulate golden 2-like transcription factor by assembling a cullin 4-based ubiquitin ligase in tomato. New Phytologist. 209(3):1028-1039.

Interpretive Summary: CULLIN4-RING ubiquitin ligases (CRL4s) as well as their targets are fundamental regulators functioning in many key developmental and stress responses in eukaryotes. In tomato (Solanum lycopersicum), molecular cloning has revealed that the underlying genes of natural spontaneous mutations high pigment 1 (hp1), high pigment 2 (hp2) and uniform ripening (u) encode UV-DAMAGED DNA BINDING PROTEIN 1 (DDB1), DE-ETIOLATED 1 (DET1) and GOLDEN 2-LIKE (GLK2), respectively. However, the molecular basis of the opposite actions of tomato GLK2 vs CUL4-DDB1-DET1 complex on regulating plastid level and fruit quality remains unknown. Here, we provide molecular evidence showing that the tomato GLK2 protein is a substrate of the CUL4-DDB1-DET1 ubiquitin ligase complex for proteasome degradation. SlGLK2 is degraded by the ubiquitin-proteasome system, which is mainly determined by two lysine residues (K11 and K253). SlGLK2 associates with the CUL4-DDB1-DET1 E3 complex in plant cells. Genetically impairing CUL4, DDB1 or DET1 results in a retardation of SlGLK2 degradation by the 26S proteasome. These findings are relevant to the potential of nutrient accumulation in tomato fruit by mediating the plastid level and contribute to a deeper understanding of an important regulatory loop, linking protein turnover to gene regulation.

Technical Abstract: Fleshy fruit undergo a novel developmental program that ends in the irreversible process of ripening and eventual tissue senescence. During these maturation processes, fruit undergo numerous physiological, biochemical and structural alterations, making them more attractive to seed dispersal organisms. Here we provide molecular evidence that targeted protein degradation through a molecular tag called ubiquitin, contributes to control of fruit chloroplast levels which in turn influences the photosynthetic capacity of the unripe fruit and eventual pigmentation (color) of the ripe fruit. As photosynthesis contributes to sugar content and color results from important antioxidants and vitamin precursors, chloroplast content has a direct correlation to fruit taste, appearance and nutritional qualities.