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Bacterial effector activates jasmonate signaling by directly targeting JAZ transcriptional repressors.

Jiang S, Yao J, Ma KW, Zhou H, Song J, He SY, Ma W - PLoS Pathog. (2013)

Bottom Line: Here, we show that the Pseudomonas syringae T3SE HopZ1a, a member of the widely distributed YopJ effector family, directly interacts with jasmonate ZIM-domain (JAZ) proteins through the conserved Jas domain in plant hosts.These results highlight a novel example by which a bacterial effector directly manipulates the core regulators of phytohormone signaling to facilitate infection.The targeting of JAZ repressors by both coronatine toxin and HopZ1 effector suggests that the JA receptor complex is potentially a major hub of host targets for bacterial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California, United States of America ; Center for Plant Cell Biology, University of California, Riverside, California, United States of America.

ABSTRACT
Gram-negative bacterial pathogens deliver a variety of virulence proteins through the type III secretion system (T3SS) directly into the host cytoplasm. These type III secreted effectors (T3SEs) play an essential role in bacterial infection, mainly by targeting host immunity. However, the molecular basis of their functionalities remains largely enigmatic. Here, we show that the Pseudomonas syringae T3SE HopZ1a, a member of the widely distributed YopJ effector family, directly interacts with jasmonate ZIM-domain (JAZ) proteins through the conserved Jas domain in plant hosts. JAZs are transcription repressors of jasmonate (JA)-responsive genes and major components of the jasmonate receptor complex. Upon interaction, JAZs can be acetylated by HopZ1a through a putative acetyltransferase activity. Importantly, P. syringae producing the wild-type, but not a catalytic mutant of HopZ1a, promotes the degradation of HopZ1-interacting JAZs and activates JA signaling during bacterial infection. Furthermore, HopZ1a could partially rescue the virulence defect of a P. syringae mutant that lacks the production of coronatine, a JA-mimicking phytotoxin produced by a few P. syringae strains. These results highlight a novel example by which a bacterial effector directly manipulates the core regulators of phytohormone signaling to facilitate infection. The targeting of JAZ repressors by both coronatine toxin and HopZ1 effector suggests that the JA receptor complex is potentially a major hub of host targets for bacterial pathogens.

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HopZ1a interacts with AtJAZs.(A) HopZ1a interacts with AtJAZs in vitro. Precipitation of MBP-AtJAZ-HIS with GST-HopZ1a was detected by western blots before (Input) and after affinity purification (Pull-down) using anti-HIS antibody. (B) Bimolecular fluorescence complementation analysis showing the interaction between HopZ1a and AtJAZ6 in planta. HopZ1a(C216A)-nYFP and AtJAZ6-cYFP were co-expressed in N. benthamiana. Fluorescence in the infiltrated leaves was monitored by confocal microscopy at 48 hours post Agro-infiltration. DAPI was used to stain the nuclei. These experiments were repeated three times with similar results.
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ppat-1003715-g003: HopZ1a interacts with AtJAZs.(A) HopZ1a interacts with AtJAZs in vitro. Precipitation of MBP-AtJAZ-HIS with GST-HopZ1a was detected by western blots before (Input) and after affinity purification (Pull-down) using anti-HIS antibody. (B) Bimolecular fluorescence complementation analysis showing the interaction between HopZ1a and AtJAZ6 in planta. HopZ1a(C216A)-nYFP and AtJAZ6-cYFP were co-expressed in N. benthamiana. Fluorescence in the infiltrated leaves was monitored by confocal microscopy at 48 hours post Agro-infiltration. DAPI was used to stain the nuclei. These experiments were repeated three times with similar results.

Mentions: Because GmJAZ1 is an ortholog of Arabidopsis JAZ proteins (AtJAZs), we examined whether HopZ1a also targets AtJAZs. Arabidopsis produces twelve JAZ orthologs (Fig. S4). Among them, seven were tested for their interactions with HopZ1a using in vitro pull-down. Our data showed that AtJAZ2, AtJAZ5, AtJAZ6, AtJAZ8 and AtJAZ12 interacted with HopZ1a in vitro (Fig. 3A). Although AtJAZ1 shares the highest sequence similarity with GmJAZ1 (Fig. S4), the interaction of AtJAZ1 with HopZ1a could not be determined because we were unable to express AtJAZ1 in E. coli at a level suitable for the pull-down assay.


Bacterial effector activates jasmonate signaling by directly targeting JAZ transcriptional repressors.

Jiang S, Yao J, Ma KW, Zhou H, Song J, He SY, Ma W - PLoS Pathog. (2013)

HopZ1a interacts with AtJAZs.(A) HopZ1a interacts with AtJAZs in vitro. Precipitation of MBP-AtJAZ-HIS with GST-HopZ1a was detected by western blots before (Input) and after affinity purification (Pull-down) using anti-HIS antibody. (B) Bimolecular fluorescence complementation analysis showing the interaction between HopZ1a and AtJAZ6 in planta. HopZ1a(C216A)-nYFP and AtJAZ6-cYFP were co-expressed in N. benthamiana. Fluorescence in the infiltrated leaves was monitored by confocal microscopy at 48 hours post Agro-infiltration. DAPI was used to stain the nuclei. These experiments were repeated three times with similar results.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814404&req=5

ppat-1003715-g003: HopZ1a interacts with AtJAZs.(A) HopZ1a interacts with AtJAZs in vitro. Precipitation of MBP-AtJAZ-HIS with GST-HopZ1a was detected by western blots before (Input) and after affinity purification (Pull-down) using anti-HIS antibody. (B) Bimolecular fluorescence complementation analysis showing the interaction between HopZ1a and AtJAZ6 in planta. HopZ1a(C216A)-nYFP and AtJAZ6-cYFP were co-expressed in N. benthamiana. Fluorescence in the infiltrated leaves was monitored by confocal microscopy at 48 hours post Agro-infiltration. DAPI was used to stain the nuclei. These experiments were repeated three times with similar results.
Mentions: Because GmJAZ1 is an ortholog of Arabidopsis JAZ proteins (AtJAZs), we examined whether HopZ1a also targets AtJAZs. Arabidopsis produces twelve JAZ orthologs (Fig. S4). Among them, seven were tested for their interactions with HopZ1a using in vitro pull-down. Our data showed that AtJAZ2, AtJAZ5, AtJAZ6, AtJAZ8 and AtJAZ12 interacted with HopZ1a in vitro (Fig. 3A). Although AtJAZ1 shares the highest sequence similarity with GmJAZ1 (Fig. S4), the interaction of AtJAZ1 with HopZ1a could not be determined because we were unable to express AtJAZ1 in E. coli at a level suitable for the pull-down assay.

Bottom Line: Here, we show that the Pseudomonas syringae T3SE HopZ1a, a member of the widely distributed YopJ effector family, directly interacts with jasmonate ZIM-domain (JAZ) proteins through the conserved Jas domain in plant hosts.These results highlight a novel example by which a bacterial effector directly manipulates the core regulators of phytohormone signaling to facilitate infection.The targeting of JAZ repressors by both coronatine toxin and HopZ1 effector suggests that the JA receptor complex is potentially a major hub of host targets for bacterial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California, United States of America ; Center for Plant Cell Biology, University of California, Riverside, California, United States of America.

ABSTRACT
Gram-negative bacterial pathogens deliver a variety of virulence proteins through the type III secretion system (T3SS) directly into the host cytoplasm. These type III secreted effectors (T3SEs) play an essential role in bacterial infection, mainly by targeting host immunity. However, the molecular basis of their functionalities remains largely enigmatic. Here, we show that the Pseudomonas syringae T3SE HopZ1a, a member of the widely distributed YopJ effector family, directly interacts with jasmonate ZIM-domain (JAZ) proteins through the conserved Jas domain in plant hosts. JAZs are transcription repressors of jasmonate (JA)-responsive genes and major components of the jasmonate receptor complex. Upon interaction, JAZs can be acetylated by HopZ1a through a putative acetyltransferase activity. Importantly, P. syringae producing the wild-type, but not a catalytic mutant of HopZ1a, promotes the degradation of HopZ1-interacting JAZs and activates JA signaling during bacterial infection. Furthermore, HopZ1a could partially rescue the virulence defect of a P. syringae mutant that lacks the production of coronatine, a JA-mimicking phytotoxin produced by a few P. syringae strains. These results highlight a novel example by which a bacterial effector directly manipulates the core regulators of phytohormone signaling to facilitate infection. The targeting of JAZ repressors by both coronatine toxin and HopZ1 effector suggests that the JA receptor complex is potentially a major hub of host targets for bacterial pathogens.

Show MeSH
Related in: MedlinePlus