14-3-3 Mediates Transcriptional Regulation by Modulating Nucleocytoplasmic Shuttling of Tobacco DNA-binding Protein Phosphatase-1

María José Castelló,Pablo Vera,José L Carrasco

doi:10.1074/jbc.m512611200

Abstract

Tobacco DBP1 is the founding member of a novel class of plant transcription factors featuring sequence-specific DNA binding and protein phosphatase activity. To understand the mechanisms underlying the function of this family of transcriptional regulators, we have identified the tobacco 14-3-3 isoform G as the first protein interacting with a DBP factor. 14-3-3 recognition involves the N-terminal region of DBP1, which also supports the DNA binding activity attributed to DBP1. The relevance of this interaction is reinforced by its conservation in Arabidopsis plants, where the closest relative of DBP1 in this species also interacts with a homologous 14-3-3 protein through its N-terminal region. Furthermore, we show that in planta 14-3-3 G is directly involved in regulating DBP1 function by promoting nuclear export and subsequent cytoplasmic retention of DBP1 under conditions that in turn alleviate DBP1-mediated repression of target gene expression.

Highlights

Sentative of a novel class of transcription factors endowed with protein phosphatase activity [3]
Toward the elucidation of the mechanistic basis underlying the regulatory function of DBP factors we report on the identification of the specific interaction of tobacco DBP1 with 14-3-3 isoform G and demonstrate that this interaction mediates a nucleocytoplasmic shuttling of DBP1
Identification of DBP1-interacting Proteins—To identify proteins involved in the regulatory mechanism mediated by DBP1, we performed a yeast two-hybrid screen of a tobacco GAL4AD-cDNA library using full-length tobacco DBP1 as bait

Summary

Introduction

Sentative of a novel class of transcription factors endowed with protein phosphatase activity [3]. Plant Transient Expression Assay by Leaf Infiltration of Agrobacterium tumefaciens—The cDNA sequences encoding the full-length DBP1 protein and the C-terminal region were cloned in-frame with the smGFP4 coding sequence into the pVR-GFP-Ct Gateway vector.

Results

Conclusion