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Query: UNIPROT:P62988 (Ubiquitin)
 4,326 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ubiquitin is well established as a major modifier of signalling in eukaryotes. However, the extent to which plants rely on ubiquitin for regulating their lifecycle is only recently becoming apparent. This is underlined by the over-representation of genes encoding ubiquitin-metabolizing enzymes in Arabidopsis when compared with other model eukaryotes. The main characteristic of ubiquitination is the conjugation of ubiquitin onto lysine residues of acceptor proteins. In most cases the targeted protein is rapidly degraded by the 26S proteasome, the major proteolysis machinery in eukaryotic cells. The ubiquitin-proteasome system is responsible for removing most abnormal peptides and short-lived cellular regulators, which, in turn, control many processes. This allows cells to respond rapidly to intracellular signals and changing environmental conditions. This review maps out the roles of the components of the ubiquitin-proteasome system with emphasis on areas where future research is urgently needed. We provide a flavour of the diverse aspects of plant lifecycle where the ubiquitin-proteasome system is implicated. We aim to highlight common themes using key examples that reiterate the importance of the ubiquitin-proteasome system to plants. The future challenge in plant biology is to define the targets for ubiquitination, their interactors and their molecular function within the regulatory context.
New Phytol 2012 Oct
PMID:The ubiquitin-proteasome system: central modifier of plant signalling. 2289 62

Ubiquitin-mediated regulation responds rapidly to specific stimuli; this rapidity is particularly important for defense responses to pathogen attack. Here, we investigated the role of the E3 ubiquitin ligase Erysiphe necator-induced RING finger protein 1 (EIRP1) in the defense response of Chinese wild grapevine Vitis pseudoreticulata. The regulatory function of E3 ubiquitin ligase EIRP1 was investigated using molecular, genetic and biochemical approaches. EIRP1 encodes a C3HC4-type Really Interesting New Gene (RING) finger protein that harbors E3 ligase activity. This activity requires the conserved RING domain, and VpWRKY11 also interacts with EIRP1 through the RING domain. VpWRKY11 localizes to the nucleus and activates W-box-dependent transcription in planta. EIRP1 targeted VpWRKY11 in vivo, resulting in VpWRKY11 degradation. The expression of EIRP1 and VpWRKY11 responds rapidly to powdery mildew in Vitis pseudoreticulata grapevine; also, overexpression of EIRP1 in Arabidopsis confers enhanced resistance to the pathogens Golovinomyces cichoracearum and Pseudomonas syringae pv tomato DC3000. Our data suggest that the EIRP1 E3 ligase positively regulates plant disease resistance by mediating proteolysis of the negative regulator VpWRKY11 via degradation by the 26S proteasome.
New Phytol 2013 Nov
PMID:The Chinese wild grapevine (Vitis pseudoreticulata) E3 ubiquitin ligase Erysiphe necator-induced RING finger protein 1 (EIRP1) activates plant defense responses by inducing proteolysis of the VpWRKY11 transcription factor. 2390 47

The ubiquitin-like modifier (UBL) SUMO (Small Ubiquitin-Like Modifier) regulates protein function. Structural rather than sequence homology typifies UBL families. However, individual UBL types, such as SUMO, show remarkable sequence conservation. Selection pressure also operates at the SUMO gene copy number, as increased SUMO levels activate immunity and alter flowering time in Arabidopsis. We show how, despite this selection pressure, the SUMO family has diversified into eight paralogues in Arabidopsis. Relationships between the paralogues were investigated using genome collinearity and gene tree analysis. We show that palaeopolyploidy followed by tandem duplications allowed expansion and then diversification of the SUMO genes. For example, Arabidopsis SUMO5 evolved from the pan-eudicot palaeohexaploidy event (gamma), which yielded three SUMO copies. Two gamma copies were preserved as archetype SUMOs, suggesting subfunctionalization, whereas the third copy served as a hotspot for SUMO diversification. The Brassicaceae-specific alpha duplication then caused the duplication of one archetype gamma copy, which, by subfunctionalization, allowed the retention of both SUMO1 and SUMO2. The other archetype gamma copy was simultaneously pseudogenized (SUMO4/6). A tandem duplication of SUMO2 subsequently yielded SUMO3 in the Brassicaceae crown group. SUMO3 potentially neofunctionalized in Arabidopsis, but it is lost in many Brassicaceae. Our advanced methodology allows the study of the birth and fixation of other paralogues in plants.
New Phytol 2016 07
PMID:Whole-genome duplications followed by tandem duplications drive diversification of the protein modifier SUMO in Angiosperms. 2693 36

Contents Summary 995 I. Introduction 995 II. The plant Ub machinery 996 III. From Ub to Ub linkage types in plants 997 IV. Increasing analytical resolution for K63 polyUb in plants 998 V. How to build K63 polyUb chains? 998 VI. Cellular roles of K63 polyUb in plants 999 VII. Physiological roles of K63 polyUb in plants 1004 VIII. Future perspectives: towards the next level of the Ub code 1006 Acknowledgements 1006 References 1007 SUMMARY: Ubiquitination is a post-translational modification essential for the regulation of eukaryotic proteins, having an impact on protein fate, function, localization or activity. What originally appeared to be a simple system to regulate protein turnover by the 26S proteasome is now known to be the most intricate regulatory process cells have evolved. Ubiquitin can be arranged in countless chain assemblies, triggering various cellular outcomes. Polyubiquitin chains using lysine-63 from ubiquitin represent the second most abundant type of ubiquitin modification. Recent studies have exposed their common function in proteasome-independent functions in non-plant model organisms. The existence of lysine-63 polyubiquitination in plants is, however, only just emerging. In this review, we discuss the recent advances on the characterization of ubiquitin chains and the molecular mechanisms driving the formation of lysine-63-linked ubiquitin modifications. We provide an overview of the roles associated with lysine-63 polyubiquitination in plant cells in the light of what is known in non-plant models. Finally, we review the crucial roles of lysine-63 polyubiquitin-dependent processes in plant growth, development and responses to environmental conditions.
New Phytol 2018 02
PMID:Proteasome-independent functions of lysine-63 polyubiquitination in plants. 2919 34