ABSTRACT
Membrane localized transcription factors play essential roles in various plant developmental processes. The XVP/NAC003 protein is a NAC domain transcription factor associated with the plasma membrane and involved in the TDIF-PXY signaling during vascular development. We report here the mechanisms of XVP membrane localization and its nuclear translocation. Using a transient transformation approach, we found that XVP is associated with the plasma membrane through positively charged KR-rich regions. Mutagenesis studies found that the threonine amino acid at position 354 (T354) is critical for XVP translocation to the nucleus. In particular, the threonine to alanine mutation (T354A) resulted in a partial nucleus localization, while threonine to aspartic acid (T354D) mutation showed no effect on protein localization, indicating that dephosphorylation at T354 may serve as a nucleus translocation signal. This research sheds new light on the nucleus partitioning of plasma membrane-associated transcription factors.
