Detecting a novel molecular interaction involved in epigenetic control of FLC expression in Arabidopsis using yeast two hybrid system

Initiation of flowering in plants is controlled by various factors such as photoperiod, cold, hormones and epigenetic effects. A major pathway in this process is the epigenetic control of FLC gene, whose expression inhibits the flowering initiation. Removing acetyl groups from FLC gene histons, by MSI4 protein represses FLC expression, and thus, flowering is initiated. However, the molecular mechanism of this protein is largely unknown. In this research, we used the Yeast Two Hybrid System (Y2HS) to study protein-protein interactions, to find proteins interacting with MSI4. Therefore, first, we cloned the MSI4 gene in proper Y2HS vector. Then, cDNA bank of Arabidopsis thaliana was screened by MSI4 as bait to prey the interactors of MSI4. The protein trapped by this method was PKT3 (Peroxisomal 3-Ketoacyl-CoA Thiolase 3), which is an acetylcoacyl transferase. The function of this protein is to release acetyl groups and deliver them to other molecules, and therefore, it has significant role in many crucial cell processes. This interaction was confirmed by cloning the complete cDNA of PKT3 as well as its homologue, PKT4. The interaction of MSI4-PKT3 is reported here for the first time and opens new horizons for more studies on MSI4 functional mechanism. This finding can be useful in regulation of flowering time in fruits and crops through genetic engineering of this pathway for example by alteration of PKT4 regulation.