MPSR1 is a cytoplasmic PQC E3 ligase for eliminating emergent misfolded proteins in
            <i>Arabidopsis thaliana</i>

Kim, Jong Hum; Cho, Seok Keun; Oh, Tae Woo; Ryu, Moon Young; Yang, Seong Wook; Kim, Woo Taek

doi:10.1073/pnas.1713574114

Cited by 17 publications

(33 citation statements)

References 48 publications

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“…3D). To rule out the possibility that potential side effects of Tm treatment rather than the ER stress could lead to a cytosolic reduction, we adopted the L-proline analog azetidine-2-carboxylic acid (AZC), which causes ER stress by competing with D-proline for incorporation into newly synthesized proteins, causing protein misfolding (42). We used two concentrations of AZC and found that the AZC treatment also resulted in a cytosolic reduction of roGFP2 in a dosedependent manner compared with untreated conditions (SI Appendix, Fig.…”

Section: Resultsmentioning

confidence: 99%

Salicylic acid-independent role of NPR1 is required for protection from proteotoxic stress in the plant endoplasmic reticulum

Lai

Renna

Yarema

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The unfolded protein response (UPR) is an ancient signaling pathway designed to protect cells from the accumulation of unfolded and misfolded proteins in the endoplasmic reticulum (ER). Because misregulation of the UPR is potentially lethal, a stringent surveillance signaling system must be in place to modulate the UPR. The major signaling arms of the plant UPR have been discovered and rely on the transcriptional activity of the transcription factors bZIP60 and bZIP28 and on the kinase and ribonuclease activity of IRE1, which splices mRNA to activate bZIP60. Both bZIP28 and bZIP60 modulate UPR gene expression to overcome ER stress. In this study, we demonstrate at a genetic level that the transcriptional role of bZIP28 and bZIP60 in ER-stress responses is antagonized by nonexpressor of PR1 genes 1 (NPR1), a critical redox-regulated master regulator of salicylic acid (SA)-dependent responses to pathogens, independently of its role in SA defense. We also establish that the function of NPR1 in the UPR is concomitant with ER stress-induced reduction of the cytosol and translocation of NPR1 to the nucleus where it interacts with bZIP28 and bZIP60. Our results support a cellular role for NPR1 as well as a model for plant UPR regulation whereby SA-independent ER stress-induced redox activation of NPR1 suppresses the transcriptional role of bZIP28 and bZIP60 in the UPR.

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Section: Resultsmentioning

confidence: 99%

Salicylic acid-independent role of NPR1 is required for protection from proteotoxic stress in the plant endoplasmic reticulum

Lai

Renna

Yarema

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…Leaf protoplasts of 35S:GFP-TUB6 were transfected with the pBI221 empty vector or pBI221 harboring the 35S:29Flag-JUL1 construct. The in vivo co-IP assay using anti-GFP and anti-Flag antibodies was conducted as described previously (Kim et al, 2017). For in vitro pull-down assay, MBP, MBP-SPR1, and MBP-JUL1 were incubated with tubulin purified from porcine brain tissues (Cytoskeleton, Inc., Denver, CO, USA, http://cytoske leton.com) in the presence of amylose resin.…”

Section: Subcellular Localization In Vivo Co-ip and In Vitro Pulldomentioning

confidence: 99%

Arabidopsis RING E3 ubiquitin ligase JUL1 participates in ABA‐mediated microtubule depolymerization, stomatal closure, and tolerance response to drought stress

Kim

Cho

et al. 2020

The Plant Journal

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SUMMARY Ubiquitination is a critical post‐translational protein modification that has been implicated in diverse cellular processes, including abiotic stress responses, in plants. In the present study, we identified and characterized a T‐DNA insertion mutant in the At5g10650 locus. Compared to wild‐type Arabidopsis plants, at5g10650 progeny were hyposensitive to ABA at the germination stage. At5g10650 possessed a single C‐terminal C3HC4‐type Really Interesting New Gene (RING) motif, which was essential for ABA‐mediated germination and E3 ligase activity in vitro. At5g10650 was closely associated with microtubules and microtubule‐associated proteins in Arabidopsis and tobacco leaf cells. Localization of At5g10650 to the nucleus was frequently observed. Unexpectedly, At5g10650 was identified as JAV1‐ASSOCIATED UBIQUITIN LIGASE1 (JUL1), which was recently reported to participate in the jasmonate signaling pathway. The jul1 knockout plants exhibited impaired ABA‐promoted stomatal closure. In addition, stomatal closure could not be induced by hydrogen peroxide and calcium in jul1 plants. jul1 guard cells accumulated wild‐type levels of H2O2 after ABA treatment. These findings indicated that JUL1 acts downstream of H2O2 and calcium in the ABA‐mediated stomatal closure pathway. Typical radial arrays of microtubules were maintained in jul1 guard cells after exposure to ABA, H2O2, and calcium, which in turn resulted in ABA‐hyposensitive stomatal movements. Finally, jul1 plants were markedly more susceptible to drought stress than wild‐type plants. Overall, our results suggest that the Arabidopsis RING E3 ligase JUL1 plays a critical role in ABA‐mediated microtubule disorganization, stomatal closure, and tolerance to drought stress.

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“…However, they are apparently not equally redundant, as overexpression of SNIPER2 exhibits distinct developmental defects while SNIPER1 overexpression is fully WT‐like in morphology. SNIPER2 (also named as MPSR1) was previously reported as a cytoplasmic chaperone‐independent protein quality control (PQC) E3 ligase for sensing and ubiquitinating misfolded proteins for their degradation (Kim et al , ). In addition, inverse correlation between MPSR1 and chaperone protein was observed for cytoplasmic protein quality control in response to proteotoxic stress (Kim et al , ).…”

Section: Discussionmentioning

confidence: 99%

Plant E3 ligases SNIPER 1 and SNIPER 2 broadly regulate the homeostasis of sensor NLR immune receptors

Tong

Tian

et al. 2020

The EMBO Journal

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In both plants and animals, nucleotide‐binding leucine‐rich repeat (NLR) immune receptors perceive pathogen‐derived molecules to trigger immunity. Global NLR homeostasis must be tightly controlled to ensure sufficient and timely immune output while avoiding aberrant activation, the mechanisms of which are largely unclear. In a previous reverse genetic screen, we identified two novel E3 ligases, SNIPER1 and its homolog SNIPER2, both of which broadly control the levels of NLR immune receptors in Arabidopsis. Protein levels of sensor NLRs (sNLRs) are inversely correlated with SNIPER1 amount and the interactions between SNIPER1 and sNLRs seem to be through the common nucleotide‐binding (NB) domains of sNLRs. In support, SNIPER1 can ubiquitinate the NB domains of multiple sNLRs in vitro. Our study thus reveals a novel process of global turnover of sNLRs by two master E3 ligases for immediate attenuation of immune output to effectively avoid autoimmunity. Such unique mechanism can be utilized in the future for engineering broad‐spectrum resistance in crops to fend off pathogens that damage our food supply.

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MPSR1 is a cytoplasmic PQC E3 ligase for eliminating emergent misfolded proteins in Arabidopsis thaliana

Cited by 17 publications

References 48 publications

Salicylic acid-independent role of NPR1 is required for protection from proteotoxic stress in the plant endoplasmic reticulum

Salicylic acid-independent role of NPR1 is required for protection from proteotoxic stress in the plant endoplasmic reticulum

Arabidopsis RING E3 ubiquitin ligase JUL1 participates in ABA‐mediated microtubule depolymerization, stomatal closure, and tolerance response to drought stress

Plant E3 ligases SNIPER 1 and SNIPER 2 broadly regulate the homeostasis of sensor NLR immune receptors

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