Biology subjects

Pfitzner, A. J. P.

Publications and source records attributed to Pfitzner, A. J. P..

4 recordsLinked to original sources

bioRxiv2024

Arabidopsis NIM1-INTERACTING1 (NIMIN1) is a multi-domain protein controlling transition from systemic acquired resistance (SAR) to cell death

O_LINIM1-INTERACTING (NIMIN) proteins were identified by interaction with the systemic acquired resistance (SAR) key regulator NPR1. The Arabidopsis family comprises four related, yet distinct members. Ample evidence predicts that NIMIN1 is a multi-domain protein which comes into action after the onset of salicylic acid (SA) signaling prior to induction of the PR-1 defense gene. C_LIO_LIBioinformatics, protein-protein interaction assays and expression studies in tobacco were applied to explore functions of NIMIN1. C_LIO_LIThe N-terminal sequence encompassing amino acids 1 to 15 conveyed accumulation of NIMIN1 protein in planta. This newly identified segment and the known conserved NIMIN1 domains, i.e., two distinct NPR1 binding sites and an EAR motif, are neatly separated from each other by disordered regions. Co-expression of NIMIN1 and NPR1 reinforced accumulation of NPR1 protein while ectopic overexpression of NIMIN1 promoted emergence of cell death driven by the EAR motif and disturbed development of tobacco plants. C_LIO_LIWe suggest that NIMIN1 acts as a dynamic signaling agent controlling transition of pathogen-infected leaves from survival to tissue collapse. Initially, NIMIN1 binding renders the NPR1 transcription complex sensitive to the SAR signal SA enabling PR-1 transcription. At high levels of SA, NIMIN1 is outcompeted by SA from the NPR1 C-terminus, and accumulating NIMIN1 engages via its EAR motif with TOPLESS-RELATED3, thereby affecting global hormone signaling and inducing cell death in severely endangered tissue. C_LI

plant biology↗

bioRxiv2022

Differential binding of salicylic acid, phenolic acid derivatives and co- factors determines the roles of Arabidopsis NPR1 to NPR4 in plant immunity

SummaryO_LIGenetic studies have demonstrated that NPR1 is the key positive regulator of salicylic acid (SA)-induced PR-1 gene induction and systemic acquired resistance (SAR). In Arabidopsis, family members NPR1 to NPR4 share domain architecture. C_LIO_LIYeast hybrid assays were used to explore biochemical capabilities of NPR1 to NPR4. C_LIO_LIAll NPR1 to NPR4 are responsive to SA. SA perception proceeds via the conserved arginine embedded in a C-terminal LENRV-like motif. Clade 2 proteins NPR3 and NPR4 perceive SA directly, while clade 1 members NPR1 and NPR2 require interaction with partner proteins NIMIN1/NIMIN2 and TGA factors, respectively, to enable SA sensing. Intriguingly, NPR3 is considerably more sensitive to the synthetic analog 3,5-dichloroanthranilic acid than to SA, and all NPR1 to NPR4 are able to sense the microbial metabolite 6-methyl SA. C_LIO_LIWe suggest that the plant{acute}s ability to track SA and phenolic acid derivatives through NPR proteins has evolved to support diverse defense signaling outputs that are activated in parallel by agonists which may be of microbial or plant origin. In this line, NPR1-NIMIN2/NIMIN1 complex is the prime receptor for SA synthesized by plants in response to microbial attack, while NPR3 induces defense different from SAR primarily via unrecognized signal molecules. C_LI

plant biology↗

bioRxiv2019

Salicylic acid-driven association of LENRV and NIMIN1/NIMIN2 binding domain regions in the C-terminus of tobacco NPR1 transduces SAR signal

O_LINONEXPRESSOR OF PATHOGENESIS-RELATED (PR) GENES1 (NPR1) is the central regulator of salicylic acid (SA)-induced PR-1 gene expression and systemic acquired resistance (SAR). The mechanism how SA is transduced through NPR1 is discussed controversially. Previously, we showed that Arabidopsis and tobacco (Nt) NPR1 contain two domains in their C-terminal thirds with relevance to SA signaling. SA sensitivity of NPR1 relies on the arginine residue in the LENRV motif, and SA-induced NIM1-INTERACTING (NIMIN, N) proteins bind to a highly conserved sequence termed N1/N2 binding domain (BD). C_LIO_LIWe demonstrate that LENRV and N1/N2BD regions of tobacco NPR1, separated from each other, interact in yeast, in vitro, in plant and in animal cells. Physical association of LENRV and N1/N2BD parts is enhanced considerably by SA and functional analogs, but not by a non-functional analog. Furthermore, physical association requires R431 and is most effective with intact LENRV and N1/N2BD interfaces. C_LIO_LIAssociation of separated LENRV and N1/N2BD parts by SA reconstitutes a functional NtNPR1 C-terminus, displaying transcription activity and able to interact with TGA transcription factors at two distinct sites. C_LIO_LITobacco NIMIN proteins can assemble LENRV and N1/N2BD parts into ternary complexes suggesting that NIMINs shape the NPR1 C-terminus to modulate SA signaling. C_LI

plant biology↗

bioRxiv2018

Tobacco TGA7 mediates gene expression dependent and independent of salicylic acid

Basic region leucine zipper (bZIP) transcription factors of the TGA family control gene expression in response to diverse stimuli. Arabidopsis clade II and clade III TGA factors mediate salicylic acid (SA)-induced expression of PATHOGENESIS-RELATED GENE1 (PR-1) via interplay with NONEXPRESSOR OF PR GENES1 (NPR1, a.k.a. NIM1). Interaction with TGA factors occurs through the central ankyrin repeat domain of NPR1. In a yeast two-hybrid screen with the NPR1 bait, we identified TGA7, a novel member of the tobacco (Nt) TGA family grouping to clade III. TGA7 is most similar to NtTGA1a, and, like NtTGA1a, TGA7 displays transcription activity in yeast. Unexpectedly, TGA7 preferentially and uniquely interacts with the SA-sensitive C-terminal region of NtNPR1, demonstrating that NtNPR1 harbors multiple distinct TGA factor binding sites. Interaction with NPR1 impairs TGA7 transcription activity in yeast. Furthermore, TGA7 binding to the NtNPR1 C-terminus is outcompeted by SA-induced type 2 NIM1-INTERACTING (NIMIN) proteins. In tobacco plants, a TGA7-Gal4 DNA-binding domain chimeric protein (TGA7GBD) mediates SA-responsive reporter gene expression in young leaf tissue and spontaneous reporter activation in older leaves displaying PR-1 gene expression. Astonishingly, TGA7GBD is also able to activate the reporter independent from PR-1 gene expression in noninduced cotyledons of tobacco seedlings. Together, our findings support a model in which TGA7 mediates both SA-dependent and SA-independent gene activation controlled by the plants developmental stage and by the C-terminal region of constitutively accumulating NtNPR1.

plant biology↗