Biochemical and redox characterization of the Mediator complex and its associated transcription factor GeBPL, a GLABROUS1 enhancer binding protein

The eukaryotic Mediator integrates regulatory signals from promoter-bound transcription factors and transmits them to RNA polymerase II machinery. Although redox signaling is important in adjusting plant metabolism and development, nothing is known about a possible redox regulation of Mediator. Here, using pull-down and yeast two-hybrid assays, we demonstrate the association of MED10a, MED28 and MED32 Mediator subunits with the GLABROUS1 enhancer binding protein-like (GeBPL), a plant-specific transcription factor that binds a promoter containing CryR2 element. All the corresponding recombinant proteins form various types of covalent oligomers linked by intermolecular disulfide bonds that are reduced in vitro by the thioredoxin and/or glutathione/glutaredoxin systems. The presence of MED10a, MED28 and MED32 subunits or changes of its redox state affect the DNA-binding capacity of GeBPL suggesting that redox-driven conformational changes might modulate its activity. Overall, these results advance our understanding of how redox signaling affects transcription and identify Mediator as a novel actor in redox signaling pathways, relaying or integrating redox changes in combination to specific transcription factors as GeBPL.

Source: BJ Gene - April 16, 2015 Category: Biochemistry Authors: J Shaikhali, C Davoine, K Brännström, N ROUHIER, J Bygdell, S Björklund, G Wingsle Tags: BJ Plant Source Type: research