Phosphorylation-dependent regulation of the transcriptional activity of Arabidopsis SOG1.

Abstract

Eukaryotic organisms rely on the evolutionary conserved DNA damage response (DDR) mechanism to maintain genome integrity. Despite sharing many DDR components, plants lack the key mammalian DDR regulator called tumour suppressor P53. They use the functionally equivalent but otherwise unrelated plant-specific transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1) instead. Outside the conserved folded DNA-binding NAC domain, SOG1 is disordered and carries a net negative charge in its C-terminal tail. Using a high-throughput screening method in yeast, we located three putative SOG1 transcription activation domains (TAD). Two out of three are located in a C-terminal region and both comply with the Acidic Exposure Model of TAD function. In addition, those TADs are flanked by phosphorylation sites whose phosphorylation state contribute to the TAD's activity. The TADs biophysical properties are being determined and linked to their putative role as protein-protein interaction interfaces. Special interest goes out to the potential formation of transient structures in the disordered SOG1 C-terminus and its functional implications.