Limits...
NPR3 and NPR4 are receptors for the immune signal salicylic acid in plants.

Fu ZQ, Yan S, Saleh A, Wang W, Ruble J, Oka N, Mohan R, Spoel SH, Tada Y, Zheng N, Dong X - Nature (2012)

Bottom Line: Accordingly, the Arabidopsis npr3 npr4 double mutant accumulates higher levels of NPR1, and is insensitive to induction of systemic acquired resistance.Moreover, this mutant is defective in pathogen effector-triggered programmed cell death and immunity.Our study reveals the mechanism of SA perception in determining cell death and survival in response to pathogen challenge.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, North Carolina 27708, USA.

ABSTRACT
Salicylic acid (SA) is a plant immune signal produced after pathogen challenge to induce systemic acquired resistance. It is the only major plant hormone for which the receptor has not been firmly identified. Systemic acquired resistance in Arabidopsis requires the transcription cofactor nonexpresser of PR genes 1 (NPR1), the degradation of which acts as a molecular switch. Here we show that the NPR1 paralogues NPR3 and NPR4 are SA receptors that bind SA with different affinities. NPR3 and NPR4 function as adaptors of the Cullin 3 ubiquitin E3 ligase to mediate NPR1 degradation in an SA-regulated manner. Accordingly, the Arabidopsis npr3 npr4 double mutant accumulates higher levels of NPR1, and is insensitive to induction of systemic acquired resistance. Moreover, this mutant is defective in pathogen effector-triggered programmed cell death and immunity. Our study reveals the mechanism of SA perception in determining cell death and survival in response to pathogen challenge.

Show MeSH

Related in: MedlinePlus

SA directly regulates interactions between NPR proteinsa, Interaction between NPR1 and NPR3 in yeast two-hybrid (Y2H) assay. b, Interaction between NPR1 and NPR4 in Y2H. c, Interaction between NPR3 and NPR4 in Y2H. In a, b, and c, diploid yeast cells were spotted on plates (SD-Trp-Leu-His + 3 mM 3-aminotriazole) without (Control) or with 100 μM SA, INA (2,6-dichloroisonicotinic acid), or 4-HBA (4-hydroxybenzoic acid). AD, activation domain; BD, DNA-binding domain. 1, NPR1; 3, NPR3; 4, NPR4. d,In vitro pull-down assays between His-MBP-NPR1 and GST-NPR3 and GST-NPR4 in the presence or absence of 100 μM SA.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3376392&req=5

Figure 2: SA directly regulates interactions between NPR proteinsa, Interaction between NPR1 and NPR3 in yeast two-hybrid (Y2H) assay. b, Interaction between NPR1 and NPR4 in Y2H. c, Interaction between NPR3 and NPR4 in Y2H. In a, b, and c, diploid yeast cells were spotted on plates (SD-Trp-Leu-His + 3 mM 3-aminotriazole) without (Control) or with 100 μM SA, INA (2,6-dichloroisonicotinic acid), or 4-HBA (4-hydroxybenzoic acid). AD, activation domain; BD, DNA-binding domain. 1, NPR1; 3, NPR3; 4, NPR4. d,In vitro pull-down assays between His-MBP-NPR1 and GST-NPR3 and GST-NPR4 in the presence or absence of 100 μM SA.

Mentions: To test the possibility that SA is part of the NPR1-NPR3/4 complex, we performed yeast two-hybrid (Y2H) assay. Using NPR3 as bait and NPR1 as prey, little growth was observed on plates without SA (Fig. 2a). However, yeast growth was observed on plates supplemented with 100 μM SA or with the functional analogue of SA, INA (2, 6-dichloroisonicotinic acid)15, but not with 4-HBA (4-hydroxybenzoic acid)6, which cannot induce SAR. Interestingly, while SA promoted NPR1-NPR3 interaction, it disrupted the interaction between NPR1 and NPR4 (Fig. 2b). Moreover, NPR3 and NPR4 could form both homodimers and heterodimers with each other in the presence of SA and INA, but not 4-HBA (Fig. 2c). This suggests that NPR3 and NPR4 not only control NPR1 stability, but also self-regulate. Because NPR1 did not form homodimers with or without SA and interacted with NPR2 independent of SA (Supplementary Fig. 5), we focused on the regulatory roles of NPR3 and NPR4.


NPR3 and NPR4 are receptors for the immune signal salicylic acid in plants.

Fu ZQ, Yan S, Saleh A, Wang W, Ruble J, Oka N, Mohan R, Spoel SH, Tada Y, Zheng N, Dong X - Nature (2012)

SA directly regulates interactions between NPR proteinsa, Interaction between NPR1 and NPR3 in yeast two-hybrid (Y2H) assay. b, Interaction between NPR1 and NPR4 in Y2H. c, Interaction between NPR3 and NPR4 in Y2H. In a, b, and c, diploid yeast cells were spotted on plates (SD-Trp-Leu-His + 3 mM 3-aminotriazole) without (Control) or with 100 μM SA, INA (2,6-dichloroisonicotinic acid), or 4-HBA (4-hydroxybenzoic acid). AD, activation domain; BD, DNA-binding domain. 1, NPR1; 3, NPR3; 4, NPR4. d,In vitro pull-down assays between His-MBP-NPR1 and GST-NPR3 and GST-NPR4 in the presence or absence of 100 μM SA.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376392&req=5

Figure 2: SA directly regulates interactions between NPR proteinsa, Interaction between NPR1 and NPR3 in yeast two-hybrid (Y2H) assay. b, Interaction between NPR1 and NPR4 in Y2H. c, Interaction between NPR3 and NPR4 in Y2H. In a, b, and c, diploid yeast cells were spotted on plates (SD-Trp-Leu-His + 3 mM 3-aminotriazole) without (Control) or with 100 μM SA, INA (2,6-dichloroisonicotinic acid), or 4-HBA (4-hydroxybenzoic acid). AD, activation domain; BD, DNA-binding domain. 1, NPR1; 3, NPR3; 4, NPR4. d,In vitro pull-down assays between His-MBP-NPR1 and GST-NPR3 and GST-NPR4 in the presence or absence of 100 μM SA.
Mentions: To test the possibility that SA is part of the NPR1-NPR3/4 complex, we performed yeast two-hybrid (Y2H) assay. Using NPR3 as bait and NPR1 as prey, little growth was observed on plates without SA (Fig. 2a). However, yeast growth was observed on plates supplemented with 100 μM SA or with the functional analogue of SA, INA (2, 6-dichloroisonicotinic acid)15, but not with 4-HBA (4-hydroxybenzoic acid)6, which cannot induce SAR. Interestingly, while SA promoted NPR1-NPR3 interaction, it disrupted the interaction between NPR1 and NPR4 (Fig. 2b). Moreover, NPR3 and NPR4 could form both homodimers and heterodimers with each other in the presence of SA and INA, but not 4-HBA (Fig. 2c). This suggests that NPR3 and NPR4 not only control NPR1 stability, but also self-regulate. Because NPR1 did not form homodimers with or without SA and interacted with NPR2 independent of SA (Supplementary Fig. 5), we focused on the regulatory roles of NPR3 and NPR4.

Bottom Line: Accordingly, the Arabidopsis npr3 npr4 double mutant accumulates higher levels of NPR1, and is insensitive to induction of systemic acquired resistance.Moreover, this mutant is defective in pathogen effector-triggered programmed cell death and immunity.Our study reveals the mechanism of SA perception in determining cell death and survival in response to pathogen challenge.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, North Carolina 27708, USA.

ABSTRACT
Salicylic acid (SA) is a plant immune signal produced after pathogen challenge to induce systemic acquired resistance. It is the only major plant hormone for which the receptor has not been firmly identified. Systemic acquired resistance in Arabidopsis requires the transcription cofactor nonexpresser of PR genes 1 (NPR1), the degradation of which acts as a molecular switch. Here we show that the NPR1 paralogues NPR3 and NPR4 are SA receptors that bind SA with different affinities. NPR3 and NPR4 function as adaptors of the Cullin 3 ubiquitin E3 ligase to mediate NPR1 degradation in an SA-regulated manner. Accordingly, the Arabidopsis npr3 npr4 double mutant accumulates higher levels of NPR1, and is insensitive to induction of systemic acquired resistance. Moreover, this mutant is defective in pathogen effector-triggered programmed cell death and immunity. Our study reveals the mechanism of SA perception in determining cell death and survival in response to pathogen challenge.

Show MeSH
Related in: MedlinePlus