A Transcription Factor {gamma}MYB1 Binds to the P1BS cis-Element and Activates PLA2-{gamma} Expression with its Co-Activator {gamma}MYB2

In this study, analysis of the PLA2- promoter using a deletion series revealed that the promoter region –153 to –1 is crucial for its pollen specificity. Using a yeast one-hybrid screening assay with the PLA2- promoter and an Arabidopsis transcription factor (TF)-only library, we isolated two novel MYB-like TFs belonging to the MYB-CC family, denoted here as MYB1 and MYB2. By electrophoretic mobility shift assay, we found that these two TFs bind directly to the P1BS (phosphate starvation response 1-binding sequence) cis-element of the PLA2- promoter. MYB1 alone functioned as a transcriptional activator for PLA2- expression, whereas MYB2 directly interacted with MYB1 and enhanced its activation. Overexpression of MYB1 in the mature pollen grain led to increased expression of not only the PLA2- gene but also of several genes whose promoters contain the P1BS cis-element and which are involved in the Pi starvation response, phospholipid biosynthesis and sugar synthesis. Based on these results, we suggest that the TF MYB1 binds to the P1BS cis-element, activates the expression of PLA2- with the assistance of its co-activator, MYB2, and regulates the expression of several target genes involved in many plant metabolic reactions.
Source: Plant and Cell Physiology - Category: Cytology Authors: Tags: Regular Papers Source Type: research