Elucidating the role of highly homologous Nicotiana benthamiana ubiquitin E2 gene family members in plant immunity through an improved virus-induced gene silencing approach

Zhou, Bangjun; Zeng, Lirong

doi:10.1186/s13007-017-0210-6

Cited by 17 publications

(17 citation statements)

References 64 publications

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“…This study suggests that Fni3/Sl-Ubc13-2 and Suv positively regulate plant immunity [128]. By knocking down the Group III E2 genes in Nicotiana benthamiana via VIGS (gene silencing), it is found that these genes are necessary for plant development, immunity-associated ROS production, and suppression of immunity-associated PCD (programmed cell death) by AvrPtoB [134,135]. Besides, knocking down the expression of TaU4 gene which encodes a ubiquitin-conjugating enzyme 4 in Triticum aestivum by VIGS can slow down the development of disease symptoms and reduce Septoria sporulation (Mycosphaerella graminicola, commonly known as Septoria), indicating that TaU4 is a negative regulator for defense against the phytopathogen Septoria in wheat [123].…”

Section: Plant Immune Responsesmentioning

confidence: 81%

The Ubiquitin Conjugating Enzyme: An Important Ubiquitin Transfer Platform in Ubiquitin-Proteasome System

Liu

Tang

et al. 2020

IJMS

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Owing to a sessile lifestyle in nature, plants are routinely faced with diverse hostile environments such as various abiotic and biotic stresses, which lead to accumulation of free radicals in cells, cell damage, protein denaturation, etc., causing adverse effects to cells. During the evolution process, plants formed defense systems composed of numerous complex gene regulatory networks and signal transduction pathways to regulate and maintain the cell homeostasis. Among them, ubiquitin-proteasome pathway (UPP) is the most versatile cellular signal system as well as a powerful mechanism for regulating many aspects of the cell physiology because it removes most of the abnormal and short-lived peptides and proteins. In this system, the ubiquitin-conjugating enzyme (E2) plays a critical role in transporting ubiquitin from the ubiquitin-activating enzyme (E1) to the ubiquitin-ligase enzyme (E3) and substrate. Nevertheless, the comprehensive study regarding the role of E2 enzymes in plants remains unexplored. In this review, the ubiquitination process and the regulatory role that E2 enzymes play in plants are primarily discussed, with the focus particularly put on E2 s regulation of biological functions of the cell. especially E3s (more than 1400 potential E3s are encoded in A. thaliana genome) and E2s (37 E2s are encoded in A. thaliana genome) [8,21]. Therefore, it will be an important task for future research to uncover the role of these enzymes. UbiquitinUbiquitin, a small protein of 76 amino acids acting as a tag in post-translational modification of proteins, is absolutely conserved in vertebrates and higher plants, and only two or three amino acid residues are different even among animals, plants, and fungi [22]. The high conservatism renders ubiquitin interchangeable and universal in different species [23]. Ubiquitin is a β-grasp fold protein consisting of a 3.5-turn α-helix, a short 3 10 helix against a five-strand mixed β-sheet and seven reverse turns [24]. Ubiquitin possesses two hydrophobic surfaces. One surface consists of Ile44, Leu8, Val70, and His68 [25], and the other focuses on Ile36 that can be recognized by HECT (Homology to E6-AP C terminus) E3s, DUBs (Deubiquitinating enzymes), and UBDs (Ubiquitin binding domains) [26][27][28]. Ubiquitin contains seven lysine residues, including Lys-6, Lys-11, Lys-27, Lys-29, Lys-33, Lys-48, Lys-63 (K6, K11, K27, K29, K33, K48, and K63, respectively) [29,30]. Six of the seven Lys linkages (with a preference for Lys-48>Lys-63>Lys-11>>>Lys-33/Lys-29/Lys-6) were detected in A. thaliana [31,32]. Any one of the seven lysine residues or N-terminal Met1 residues in ubiquitin is likely to be involved in ubiquitin chain formation in vivo, and different ubiquitin linkages lead to the formation of different types of ubiquitin chains and induce diverse molecular signals in the cell [29,[33][34][35][36]. Different ways of linking ubiquitin chains and substrates result in distinct fates of the substrates. It is well-known that K48-linked chains are mediators signaling proteasom...

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Section: Plant Immune Responsesmentioning

confidence: 81%

The Ubiquitin Conjugating Enzyme: An Important Ubiquitin Transfer Platform in Ubiquitin-Proteasome System

Liu

Tang

et al. 2020

IJMS

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“…We also tested ZAR1-dependence of these effector-independent cell death phenotypes by subjecting N. benthamiana plants to virus-induced gene silencing (VIGS) [38–40] two weeks prior to transformation and induction of ZED1 expression. Although the HR-mediated cell death induced by ZED1 ‘DT’ , ZED1 V212T and HopZ1a/ZED1 wt was unaffected in plants experiencing silencing of the negative control GUS gene (Fig 7A, left), the HR induced by all of these transformations was completely abolished in plants that received a ZAR1 silencing construct (Fig 7A, right).…”

Section: Resultsmentioning

confidence: 99%

“…Transgene expression was induced by spraying whole leaves with 20 μM dexamethasone in water with 0.01% surfactant Silwet-L77 (8 - 24h following infiltrations). Gene silencing was performed as described previously [38–40], using Agrobacterium strains generously provided by Maël Baudin and Jennifer D. Lewis (University of California, Berkeley).…”

Section: Methodsmentioning

confidence: 99%

Perturbations of a Kinase-Pseudokinase Module Activate Plant Immunity

Bastedo

Seto

Martel

et al. 2019

Preprint

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The Pseudomonas syringae acetyltransferase HopZ1a is delivered directly into host cells by the type III secretion system to promote bacterial growth. However, in the model plant host Arabidopsis thaliana, HopZ1a activity results in an effector-triggered immune response (ETI) that limits bacterial proliferation. HopZ1a-triggered immunity requires the nucleotide-binding, leucine-rich repeat domain (NLR) protein, ZAR1, and the ZED1 pseudokinase. Here we demonstrate that HopZ1a can acetylate members of a family of ‘receptor-like cytoplasmic kinases’ (RLCK family VII; also known as PBS1-like kinases, or PBLs) and promote their interaction with ZED1 and ZAR1 to form a ZAR1/ZED1/PBL ternary complex. Interactions between ZED1 and PBL kinases are determined by the pseudokinase features of ZED1, and mutants designed to restore ZED1 kinase motifs can (1) bind to PBLs, (2) recruit ZAR1, and (3) trigger immunity in planta, all independently of HopZ1a. Our results suggest that interactions between these two RLCK families are promoted by perturbations of structural features that distinguish active from inactive kinase domain conformations. We propose that effector-induced interactions between ZED1/ZRK pseudokinases (RLCK family XII) and PBL kinases (RLCK family VII) provide a sensitive mechanism for detecting perturbations of either kinase family and activating ZAR1-mediated ETI.AUTHOR SUMMARYAll plants must ward off potentially infectious microbes, and those grown in large-scale crop operations are especially vulnerable to the rapid spread of disease by successful pathogens. Although many bacteria and fungi can supress plant immune responses by producing specialized virulence proteins called ‘effectors’, these effectors can also trigger immune responses that render plants resistant to infection. We studied the molecular mechanisms underlying one such effector-triggered immune response elicited by the bacterial effector HopZ1a in the model plant host Arabidopsis thaliana. We have shown that HopZ1a promotes binding between a ZED1, a ‘pseudokinase’ required for HopZ1a-triggered immunity, and several ‘true kinases’ (known as PBLs) that are likely targets of HopZ1a activity in planta. HopZ1a-induced ZED1-PBL interactions also recruit ZAR1, an Arabidopsis ‘resistance protein’ previously implicated in HopZ1a-triggered immunity. Importantly, ZED1 mutants that restore degenerate kinase motifs can bridge interactions between PBLs and ZAR1 (independently of HopZ1a) and trigger immunity in planta. Our results suggest that equilibria between active and inactive kinase domain conformations regulate ZED1-PBL interactions and formation of ternary complexes with ZAR1. Improved models describing molecular interactions between immunity determinants, effectors and effector targets will inform efforts to exploit natural diversity for development of crops with enhanced disease resistance.

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“…Ubiquitination as a major post-translational protein modification in eukaryotic cells typically entails a stepwise enzymatic cascade that is catalyzed by three different classes of enzymes, the ubiquitin-activating enzyme (E1), the ubiquitin-conjugating enzyme (E2), and the ubiquitin ligase (E3) ( Zhou and Zeng, 2017 ). During the ubiquitination process, the E2∼ubiquitin intermediate cooperates with an E3 to transfer ubiquitin to the substrate.…”

Section: Introductionmentioning

confidence: 99%

“…The group III E2 enzymes were found to be essential for plant PTI and for the suppression of host immunity by the ubiquitin ligase activity of a Pseudomonas syringae pv. tomato (Pst) effector, AvrPtoB ( Zhou et al, 2017 ; Zhou and Zeng, 2017 ). Additionally, functional redundancy among group III members was revealed for their role in PTI and in AvrPtoB-mediated suppression of plant immunity.…”

Section: Introductionmentioning

confidence: 99%

The Tomato U-Box Type E3 Ligase PUB13 Acts With Group III Ubiquitin E2 Enzymes to Modulate FLS2-Mediated Immune Signaling

Zhou

Zeng

2018

Front. Plant Sci.

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In Arabidopsis and rice, the ubiquitin ligase PUB13-mediated protein degradation plays a significant role in plant pattern-triggered immunity (PTI) and flowering time control. The Arabidopsis PUB13 has been shown to attenuate the pattern recognition receptor FLS2-mediated immune signaling by ubiquitinating FLS2 and consequently promoting its degradation by the 26S proteasome. Nevertheless, the cognate ubiquitin-conjugating enzymes (E2) with which PUB13 acts to modulate FLS2-mediated PTI are unknown. To address this question, we investigate here the tomato (Solanum lycopersicum) homolog of PUB13, SlPUB13 by utilizing the recently characterized complete set of tomato E2s. Of the 13 groups of tomato E2s, only members in group III are found to interact and act with SlPUB13. Knocking-down of the group III E2 genes enhances callose deposition and induction of the RbohB gene in the immunity-associated, early oxidative burst after flg22 treatment. The group III E2s are also found to work with SlPUB13 to ubiquitinate FLS2 in vitro and are required for PUB13-mediated degradation of FLS2 in vivo upon flg22 treatment, suggesting an essential role for group III E2s in the modulation of FLS2-mediated immune signaling by PUB13. Additionally, another immunity-associated E3, NtCMPG1 is shown to also work specifically with members of group III E2 in the in vitro ubiquitination assay, which implies the group III E2 enzymes may cooperate with many E3 ligases to regulate different aspects of PTI. Taken together, these data corroborate the notion that group III E2 enzymes play an important role in PTI and build a foundation for further functional and mechanistic characterization of tomato PUB13.

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Elucidating the role of highly homologous Nicotiana benthamiana ubiquitin E2 gene family members in plant immunity through an improved virus-induced gene silencing approach

Cited by 17 publications

References 64 publications

The Ubiquitin Conjugating Enzyme: An Important Ubiquitin Transfer Platform in Ubiquitin-Proteasome System

The Ubiquitin Conjugating Enzyme: An Important Ubiquitin Transfer Platform in Ubiquitin-Proteasome System

Perturbations of a Kinase-Pseudokinase Module Activate Plant Immunity

The Tomato U-Box Type E3 Ligase PUB13 Acts With Group III Ubiquitin E2 Enzymes to Modulate FLS2-Mediated Immune Signaling

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