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Auxin action in a cell-free system 总被引:24,自引:0,他引:24
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Arabidopsis AXR6 encodes CUL1 implicating SCF E3 ligases in auxin regulation of embryogenesis
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Hellmann H Hobbie L Chapman A Dharmasiri S Dharmasiri N del Pozo C Reinhardt D Estelle M 《The EMBO journal》2003,22(13):3314-3325
The AXR6 gene is required for auxin signaling in the Arabidopsis embryo and during postembryonic development. One of the effects of auxin is to stimulate degradation of the Aux/IAA auxin response proteins through the action of the ubiquitin protein ligase SCF(TIR1). Here we show that AXR6 encodes the SCF subunit CUL1. The axr6 mutations affect the ability of mutant CUL1 to assemble into stable SCF complexes resulting in reduced degradation of the SCF(TIR1) substrate AXR2/IAA7. In addition, we show that CUL1 is required for lateral organ initiation in the shoot apical meristem and the inflorescence meristem. These results indicate that the embryonic axr6 phenotype is related to a defect in SCF function and accumulation of Aux/IAA proteins such as BDL/IAA12. In addition, we show that CUL1 has a role in auxin response throughout the life cycle of the plant. 相似文献
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Auxin receptors: a new role for F-box proteins 总被引:15,自引:0,他引:15
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The auxin/indoleacetic acid (Aux/IAA) proteins are negative regulators of the auxin response factors (ARFs) that regulate expression of auxin-responsive genes. The Aux/IAA proteins have four conserved domains. Domain II is responsible for the rapid degradation of these proteins. Degradation of the Aux/IAA proteins, mediated by a SCF(TIR1) E3 ubiquitin protein ligase complex, is critical for auxin-regulated gene expression. Using a steroid-hormone-inducible system, we had previously shown that a protein-stability-enhancing mutation in domain II of IAA1 (iaa1) impaired diverse auxin responses. Inhibition of hypocotyl elongation, leaf expansion, and stem elongation by overexpression of iaa1 suggested that cell enlargement and/or cell division might be affected. We here examined the effects of the domain II mutation on cellular anatomy using light microscopy. Our results show that overexpression of iaa1 in Arabidopsis significantly reduced cell length and cell number and affected cell shape in inflorescences and leaves in a dexamethasone (DEX)-dependent manner. These results suggest that IAA1 might be involved in cell elongation as well as in cell division in the aerial parts of Arabidopsis plants. In addition, the formation of both phloem and xylem in leaves and stems was also impaired in a DEX-dependent manner, indicating a potential involvement of IAA1 in vascular development. 相似文献
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The role of regulated protein degradation in auxin response 总被引:11,自引:0,他引:11
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A role for phospholipase A in auxin-regulated gene expression 总被引:1,自引:0,他引:1
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The auxins, plant hormones, play a crucial role in many aspects of plant development by regulating cell division, elongation and differentiation. Toyocamycin, a nucleoside-type antibiotic, was identified as auxin signaling inhibitor in a screen of microbial extracts for inhibition of the auxin-inducible reporter gene assay. Toyocamycin specifically inhibited auxin-responsive gene expression, but did not affect other hormone-inducible gene expression. Toyocamycin also blocked auxin-enhanced degradation of the Aux/IAA repressor modulated by the SCF(TIR1) ubiquitin-proteasome pathway without inhibiting proteolytic activity of proteasome. Furthermore, toyocamycin inhibited auxin-induced lateral root formation and epinastic growth of cotyledon in the Arabidopsis thaliana plant. This evidence suggested that toyocamycin would act on the ubiquitination process regulated by SCF(TIR1) machineries. To address the structural requirements for the specific activity of toyocamycin on auxin signaling, the structure-activity relationships of nine toyocamycin-related compounds, including sangivamycin and tubercidin, were investigated. 相似文献
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Shucai Wang 《Phyton》2023,92(4):1153-1160
Light is an environmental signaling, whereas Aux/IAA proteins and Auxin Response Factors (ARFs) are regulators of auxin signalling. Aux/IAA proteins are unstable, and their degradation dependents on 26S ubiquitin-proteasome and is promoted by Auxin. Auxin binds directly to a SCF-type ubiquitin-protein ligase, TIR1, facilitates the interaction between Aux/IAA proteins and TIR1, and then the degradation of Aux/IAA proteins. A few studies have reported that some ARFs are also unstable proteins, and their degradation is also mediated by 26S proteasome. In this study, by using of antibodies recognizing endogenous ARF7 proteins, we found that protein stability of ARF7 was affected by light. By expressing MYC tagged ARF activators in protoplasts, we found that degradation of ARF7 was inhibited by 26 proteasome inhibitors. In addition, at least ARF5 and ARF19 were also unstable proteins, and degradation of ARF5 via 26S proteasome was further confirmed by using stable transformed plants overexpressing ARF5 with a GUS tag. 相似文献
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Lian Jin Qingqing Qin Yu Wang Yingying Pu Lifang Liu Xing Wen Shaoyi Ji Jianguo Wu Chunhong Wei Biao Ding Yi Li 《PLoS pathogens》2016,12(9)
The phytohormone auxin plays critical roles in regulating myriads of plant growth and developmental processes. Microbe infection can disturb auxin signaling resulting in defects in these processes, but the underlying mechanisms are poorly understood. Auxin signaling begins with perception of auxin by a transient co-receptor complex consisting of an F-box transport inhibitor response 1/auxin signaling F-box (TIR1/AFB) protein and an auxin/indole-3-acetic acid (Aux/IAA) protein. Auxin binding to the co-receptor triggers ubiquitination and 26S proteasome degradation of the Aux/IAA proteins, leading to subsequent events, including expression of auxin-responsive genes. Here we report that Rice dwarf virus (RDV), a devastating pathogen of rice, causes disease symptoms including dwarfing, increased tiller number and short crown roots in infected rice as a result of reduced sensitivity to auxin signaling. The RDV capsid protein P2 binds OsIAA10, blocking the interaction between OsIAA10 and OsTIR1 and inhibiting 26S proteasome-mediated OsIAA10 degradation. Transgenic rice plants overexpressing wild-type or a dominant-negative (degradation-resistant) mutant of OsIAA10 phenocopy RDV symptoms are more susceptible to RDV infection; however, knockdown of OsIAA10 enhances the resistance of rice to RDV infection. Our findings reveal a previously unknown mechanism of viral protein reprogramming of a key step in auxin signaling initiation that enhances viral infection and pathogenesis. 相似文献
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Terrile MC París R Calderón-Villalobos LI Iglesias MJ Lamattina L Estelle M Casalongué CA 《The Plant journal : for cell and molecular biology》2012,70(3):492-500
Previous studies have demonstrated that auxin (indole-3-acetic acid) and nitric oxide (NO) are plant growth regulators that coordinate several plant physiological responses determining root architecture. Nonetheless, the way in which these factors interact to affect these growth and developmental processes is not well understood. The Arabidopsis thaliana F-box proteins TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) are auxin receptors that mediate degradation of AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) repressors to induce auxin-regulated responses. A broad spectrum of NO-mediated protein modifications are known in eukaryotic cells. Here, we provide evidence that NO donors increase auxin-dependent gene expression while NO depletion blocks Aux/IAA protein degradation. NO also enhances TIR1-Aux/IAA interaction as evidenced by pull-down and two-hybrid assays. In addition, we provide evidence for NO-mediated modulation of auxin signaling through S-nitrosylation of the TIR1 auxin receptor. S-nitrosylation of cysteine is a redox-based post-translational modification that contributes to the complexity of the cellular proteome. We show that TIR1 C140 is a critical residue for TIR1-Aux/IAA interaction and TIR1 function. These results suggest that TIR1 S-nitrosylation enhances TIR1-Aux/IAA interaction, facilitating Aux/IAA degradation and subsequently promoting activation of gene expression. Our findings underline the importance of NO in phytohormone signaling pathways. 相似文献
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