Two Novel RING-Type Ubiquitin Ligases, RGLG3 and RGLG4, Are Essential for Jasmonate-Mediated Responses in Arabidopsis

Zhang, Xu; Wu, Qian; Ren, Jiao; Qian, Wanqiang; He, Shuchang; Huang, Ke; Yu, Xiangchun; Gao, Yin; Huang, Ping; Chen, An

doi:10.1104/pp.112.203422

Cited by 39 publications

(51 citation statements)

References 75 publications

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“…RGLG1/5 are RING-type E3 ligases that belong to a five-member family (Wu et al, 2016). Sequence alignment has revealed that RGLG1, RGLG2 and RGLG5 belong to a different branch than RGLG3/4 (Zhang et al, 2012). RGLG1 and RGLG2 show functional overlap in K63-linked polyubiquitination in plasma membrane, which is a proteasome-independent function of RGLG1 and RGLG2 (Yin et al, 2007;Romero-Barrios and Vert, 2018).…”

Section: Introductionmentioning

confidence: 99%

ABA inhibits myristoylation and induces shuttling of the RGLG1 E3 ligase to promote nuclear degradation of PP2CA

et al. 2019

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Summary Hormone‐ and stress‐induced shuttling of signaling or regulatory proteins is an important cellular mechanism to modulate hormone signaling and cope with abiotic stress. Hormone‐induced ubiquitination plays a crucial role to determine the half‐life of key negative regulators of hormone signaling. For ABA signaling, the degradation of clade‐A PP2Cs, such as PP2CA or ABI1, is a complementary mechanism to PYR/PYL/RCAR‐mediated inhibition of PP2C activity. ABA promotes the degradation of PP2CA through the RGLG1 E3 ligase, although it is not known how ABA enhances the interaction of RGLG1 with PP2CA given that they are predominantly found in the plasma membrane and the nucleus, respectively. We demonstrate that ABA modifies the subcellular localization of RGLG1 and promotes nuclear interaction with PP2CA. We found RGLG1 is myristoylated in vivo, which facilitates its attachment to the plasma membrane. ABA inhibits the myristoylation of RGLG1 through the downregulation of N‐myristoyltransferase 1 (NMT1) and promotes nuclear translocation of RGLG1 in a cycloheximide‐insensitive manner. Enhanced nuclear recruitment of the E3 ligase was also promoted by increasing PP2CA protein levels and the formation of RGLG1–receptor–phosphatase complexes. We show that RGLG1Gly2Ala mutated at the N‐terminal myristoylation site shows constitutive nuclear localization and causes an enhanced response to ABA and salt or osmotic stress. RGLG1/5 can interact with certain monomeric ABA receptors, which facilitates the formation of nuclear complexes such as RGLG1–PP2CA–PYL8. In summary, we provide evidence that an E3 ligase can dynamically relocalize in response to both ABA and increased levels of its target, which reveals a mechanism to explain how ABA enhances RGLG1–PP2CA interaction and hence PP2CA degradation.

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Section: Introductionmentioning

confidence: 99%

ABA inhibits myristoylation and induces shuttling of the RGLG1 E3 ligase to promote nuclear degradation of PP2CA

et al. 2019

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“…RGLG2 catalyzes the formation of ubiquitin Lys-63linked chains when combined with the heterodimeric E2 enzyme formed by MMZ2 and UBC35 (Yin et al, 2007). Recently, it was reported that RGLG3 and RGLG4 are essential regulators of the jasmonate pathway (Zhang et al, 2012(Zhang et al, , 2015. However, in these studies, the molecular targets of RGLG1-4 were not identified.…”

Section: Introductionmentioning

confidence: 98%

Ubiquitin Ligases RGLG1 and RGLG5 Regulate Abscisic Acid Signaling by Controlling the Turnover of Phosphatase PP2CA

et al. 2016

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Abscisic acid (ABA) is an essential hormone for plant development and stress responses. ABA signaling is suppressed by clade A PP2C phosphatases, which function as key repressors of this pathway through inhibiting ABA-activated SnRK2s (SNF1-related protein kinases). Upon ABA perception, the PYR/PYL/RCAR ABA receptors bind to PP2Cs with high affinity and biochemically inhibit their activity. While this mechanism has been extensively studied, how PP2Cs are regulated at the protein level is only starting to be explored. RING DOMAIN LIGASE5 (RGLG5) belongs to a five-member E3 ubiquitin ligase family whose target proteins remain unknown. We report that RGLG5, together with RGLG1, releases the PP2C blockade of ABA signaling by mediating PP2CA protein degradation. ABA promotes the interaction of PP2CA with both E3 ligases, which mediate ubiquitination of PP2CA and are required for ABA-dependent PP2CA turnover. Downregulation of and stabilizes endogenous PP2CA and diminishes ABA-mediated responses. Moreover, the reduced response to ABA in germination assays is suppressed in the (artificial microRNA) triple mutant, supporting a functional link among these loci. Overall, our data indicate that RGLG1 and RGLG5 are important modulators of ABA signaling, and they unveil a mechanism for activation of the ABA pathway by controlling PP2C half-life.

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“…Loss-of-function mutants in RGLG1 and RGLG2 individually have no phenotypic differences from wild type, while the double mutant is affected in auxin level and signaling, drought responses and iron deficiency responses (Yin et al, 2007;Li and Schmidt, 2010;Cheng et al, 2012). Similarly, the related RGLG3 (At5g63970) and RGLG4 (At1g79380) are functionally redundant in terms of regulating jasmonate-mediated wound responses (Zhang et al, 2012).…”

Section: Other Rings Are Functional As Single Polypeptidesmentioning

confidence: 99%

The Ubiquitination Machinery of the Ubiquitin System

Callis

2014

The Arabidopsis Book

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The protein ubiquitin is a covalent modifier of proteins, including itself. The ubiquitin system encompasses the enzymes required for catalysing attachment of ubiquitin to substrates as well as proteins that bind to ubiquitinated proteins leading them to their final fate. Also included are activities that remove ubiquitin independent of, or in concert with, proteolysis of the substrate, either by the proteasome or proteases in the vacuole. In addition to ubiquitin encoded by a family of fusion proteins, there are proteins with ubiquitin-like domains, likely forming ubiquitin's β-grasp fold, but incapable of covalent modification. However, they serve as protein-protein interaction platforms within the ubiquitin system. Multi-gene families encode all of these types of activities. Within the ubiquitination machinery "half" of the ubiquitin system are redundant, partially redundant, and unique components affecting diverse developmental and environmental responses in plants. Notably, multiple aspects of biotic and abiotic stress responses require, or are modulated by, ubiquitination. Finally, aspects of the ubiquitin system have broad utility: as components to enhance gene expression or to regulate protein abundance. This review focuses on the ubiquitination machinery: ubiquitin, unique aspects about the synthesis of ubiquitin and organization of its gene family, ubiquitin activating enzymes (E1), ubiquitin conjugating enzymes (E2) and ubiquitin ligases, or E3s. Given the large number of E3s in Arabidopsis this review covers the U box, HECT and RING type E3s, with the exception of the cullin-based E3s.

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Two Novel RING-Type Ubiquitin Ligases, RGLG3 and RGLG4, Are Essential for Jasmonate-Mediated Responses in Arabidopsis

Cited by 39 publications

References 75 publications

ABA inhibits myristoylation and induces shuttling of the RGLG1 E3 ligase to promote nuclear degradation of PP2CA

ABA inhibits myristoylation and induces shuttling of the RGLG1 E3 ligase to promote nuclear degradation of PP2CA

Ubiquitin Ligases RGLG1 and RGLG5 Regulate Abscisic Acid Signaling by Controlling the Turnover of Phosphatase PP2CA

The Ubiquitination Machinery of the Ubiquitin System

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