Interaction of NIMIN1 with NPR1 Modulates PR Gene Expression in Arabidopsis

Abstract

The Arabidopsis thaliana NONEXPRESSER OF PR GENES1 (NPR1, also known as NIM1) protein is an essential positive regulator of salicylic acid (SA)-induced PATHOGENESIS-RELATED (PR) gene expression and systemic acquired resistance (SAR). PR gene activity is regulated at the level of redox-dependent nuclear transport of NPR1. NPR1 interacts with members of the TGA family of transcription factors that are known to bind to SA-responsive elements in the PR-1 promoter.In an attempt to identify proteins involved in SA-mediated signal transduction, we previously described the isolation of three novel genes encoding distinct albeit structurally related proteins designated NIMIN1 (for NIM1-INTERACTING1), NIMIN2, and NIMIN3 that interact with NPR1 in the yeast two-hybrid system. Here, we show that NIMIN1 and NPR1 can be copurified from plant extracts, providing biochemical evidence for their interaction. We provide functional evidence for this interaction by describing transgenic plants constitutively expressing high amounts of NIMIN1. These plants show reduced SA-mediated PR gene induction and a compromised SAR, thus mimicking the described phenotype conferred by npr1. Moreover, they showed reduced RESISTANCE gene-mediated protection. These effects were dependent on the ability of NIMIN1 to interact with NPR1. Mutant plants with a T-DNA insertion in NIMIN1 as well as transgenic plants with reduced NIMIN1 mRNA levels showed hyperactivation of PR-1 gene expression after SA treatment but no effect on the disease resistance phenotype. Our results strongly suggest that NIMIN1 negatively regulates distinct functions of NPR1, providing a mechanism to modulate specific features of SAR.

XopD SUMO Protease Affects Host Transcription, Promotes Pathogen Growth, and Delays Symptom Development inXanthomonas-Infected Tomato Leaves

“…In plants, EAR motifs are found on a number of transcriptional regulators and they are sufficient to repress transcription (Ohta et al, 2001). It is not clear (Weigel et al, 2005;Kazan, 2006). Our work shows that the XopD EAR motifs are required to repress plant gene transcription, to promote maximal Xcv multiplication, and to delay the onset of disease symptoms infected tomato leaves (Figures 5 and 6).…”

“…We currently favor the model that XopD may be functioning at the level of chromatin-remodeling based on the finding that ERF7, an Arabidopsis EAR-containing protein, appears to be altering chromatin status by recruiting the corepressor SIN3 and histone deacetylase HDA19 to promoters containing GCC boxes (Song et al, 2005;Weigel et al, 2005;Kazan, 2006). Also, the overexpression of ORE7, nuclear chromatin remodeling, AThook DNA binding motif prolongs leaf longevity in Arabidopsis (Lim et al, 2007b).…”

TheArabidopsisGRAS Protein SCL14 Interacts with Class II TGA Transcription Factors and Is Essential for the Activation of Stress-Inducible Promoters

“…However, fusion of the bait protein with a heterologous DNA binding domain or fusion of the prey protein with an activation domain might hamper certain interactions. In the screen reported here, this potential drawback was circumvented by positioning three copies of the as-1 element (3x as-1) upstream of the HIS3 selectable marker gene (Weigel et al, 2005) and expressing TGA2 in trans. As as-1-bound TGA2 only weakly activates transcription in yeast, the resulting strain does not grow on selective medium when 15 mM 3-amino-1,2,4-triazole is added.…”

Análisis genético de la percepción del ácido salicílico en Arabidopsis thaliana. Caracterización de NRB4

“…De hecho, su sobreexpresión compromete respuestas defensivas como la ETI y la SAR. Además, también puede formar complejos con algunas TGAs, NPR1 y el promotor PR-1, modulando así la activación transcripcional dependiente de los TGAs (Weigel et al 2001;Weigel et al 2005).…”

“…There are two families of NPR1 interactors: TGAs (Zhang et al 1999) and NIMINs (Weigel et al 2001). Only when knocking out several genes (TGAs, Zhang et al 2003), or expressing dominant members (NIMINs, Weigel et al 2005), is a measurable phenotype observed in SA signalling.…”