RNF4 interacts with multiSUMOylated ETV4

Protein SUMOylation represents an important regulatory event that changes the activities of numerous proteins. Recent evidence demonstrates that polySUMO chains can act as a trigger to direct the ubiquitin ligase RNF4 to substrates to cause their turnover through the ubiquitin pathway. RNF4 uses multiple SUMO interaction motifs (SIMs) to bind to these chains. However, in addition to polySUMO chains, a multimeric binding surface created by the simultaneous SUMOylation of multiple residues on a protein or complex could also provide a platform for the recruitment of multi-SIM proteins like RNF4. Here we demonstrate that multiSUMOylated ETV4 can bind to RNF4 and that a unique combination of SIMs is required for RNF4 to interact with this multiSUMOylated platform. Thus RNF4 can bind to proteins that are either polySUMOylated through a single site or multiSUMOylated on several sites and raises the possibility that such multiSIM-multiSUMO interactions might be more widespread.

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Ubiquitin-Mediated Regulation of Endocytosis by Proteins of the Arrestin Family

Biochemistry Research International ◽

10.1155/2012/242764 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 56

Author(s):

Michel Becuwe ◽

Antonio Herrador ◽

Rosine Haguenauer-Tsapis ◽

Olivier Vincent ◽

Sébastien Léon

Keyword(s):

Ubiquitin Ligase ◽

Adaptor Proteins ◽

Receptor Trafficking ◽

G Protein Coupled Receptors ◽

Endocytic Pathway ◽

Ubiquitin Pathway ◽

The Core ◽

Related Proteins ◽

G Protein Coupled

In metazoans, proteins of the arrestin family are key players of G-protein-coupled receptors (GPCRS) signaling and trafficking. Following stimulation, activated receptors are phosphorylated, thus allowing the binding of arrestins and hence an “arrest” of receptor signaling. Arrestins act by uncoupling receptors from G proteins and contribute to the recruitment of endocytic proteins, such as clathrin, to direct receptor trafficking into the endocytic pathway. Arrestins also serve as adaptor proteins by promoting the recruitment of ubiquitin ligases and participate in the agonist-induced ubiquitylation of receptors, known to have impact on their subcellular localization and stability. Recently, the arrestin family has expanded following the discovery of arrestin-related proteins in other eukaryotes such as yeasts or fungi. Surprisingly, most of these proteins are also involved in the ubiquitylation and endocytosis of plasma membrane proteins, thus suggesting that the role of arrestins as ubiquitin ligase adaptors is at the core of these proteins' functions. Importantly, arrestins are themselves ubiquitylated, and this modification is crucial for their function. In this paper, we discuss recent data on the intricate connections between arrestins and the ubiquitin pathway in the control of endocytosis.

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Proteasomal Ubiquitin Receptor RPN-10 Controls Sex Determination in Caenorhabditis elegans

Molecular Biology of the Cell ◽

10.1091/mbc.e06-05-0437 ◽

2006 ◽

Vol 17 (12) ◽

pp. 5356-5371 ◽

Cited By ~ 34

Author(s):

Masumi Shimada ◽

Kenji Kanematsu ◽

Keiji Tanaka ◽

Hideyoshi Yokosawa ◽

Hiroyuki Kawahara

Keyword(s):

Caenorhabditis Elegans ◽

Sex Determination ◽

Ubiquitin Ligase ◽

26S Proteasome ◽

Female Development ◽

Ubiquitin Pathway ◽

Downstream Target ◽

Ubiquitin Binding ◽

Client Proteins ◽

Fate Decision

The ubiquitin-binding RPN-10 protein serves as a ubiquitin receptor that delivers client proteins to the 26S proteasome. Although ubiquitin recognition is an essential step for proteasomal destruction, deletion of the rpn-10 gene in yeast does not influence viability, indicating redundancy of the substrate delivery pathway. However, their specificity and biological relevance in higher eukaryotes is still enigmatic. We report herein that knockdown of the rpn-10 gene, but not any other proteasome subunit genes, sexually transforms hermaphrodites to females by eliminating hermaphrodite spermatogenesis in Caenorhabditis elegans. The feminization phenotype induced by deletion of the rpn-10 gene was rescued by knockdown of tra-2, one of sexual fate decision genes promoting female development, and its downstream target tra-1, indicating that the TRA-2–mediated sex determination pathway is crucial for the Δrpn-10–induced sterile phenotype. Intriguingly, we found that co-knockdown of rpn-10 and functionally related ubiquitin ligase ufd-2 overcomes the germline-musculinizing effect of fem-3(gf). Furthermore, TRA-2 proteins accumulated in rpn-10-defective worms. Our results show that the RPN-10–mediated ubiquitin pathway is indispensable for control of the TRA-2–mediated sex-determining pathway.

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Cul4A is required for hematopoietic stem-cell engraftment and self-renewal

Blood ◽

10.1182/blood-2006-12-064154 ◽

2007 ◽

Vol 110 (7) ◽

pp. 2704-2707 ◽

Cited By ~ 14

Author(s):

Binghui Li ◽

Nan Jia ◽

David L. Waning ◽

Feng-Chun Yang ◽

Laura S. Haneline ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Bone Marrow Transplantation ◽

Hematopoietic Stem Cell ◽

Ubiquitin Ligase ◽

Marrow Transplantation ◽

Self Renewal ◽

Ubiquitin Pathway ◽

Hematopoietic Stem ◽

Cell Engraftment

Several hematopoietic stem-cell (HSC) regulators are controlled by ubiquitin-mediated proteolysis, so the ubiquitin pathway might modulate HSC function. However, this hypothesis has not been formally tested. Cul4A encodes a core subunit of one ubiquitin ligase. Whereas Cul4A-deficient embryos die in utero, Cul4A-haploinsufficient mice are viable but exhibit abnormal hematopoiesis (fewer erythroid and primitive myeloid progenitors). Given these data, we examined whether Cul4A+/− HSCs might also be impaired. Using bone marrow transplantation assays, we determined that Cul4A+/− HSCs exhibit defects in engraftment and self-renewal capacity. These studies are the first to demonstrate that ubiquitin-mediated protein degradation is important for HSC function. Further, they indicate that a Cul4A ubiquitin ligase targets for degradation one or multiple HSC regulators.

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DNA binding reorganizes the intrinsically disordered C-terminal region of PSC in Drosophila PRC1

10.1101/2020.06.02.130492 ◽

2020 ◽

Author(s):

Jin Joo Kang ◽

Denis Faubert ◽

Jonathan Boulais ◽

Nicole J. Francis

Keyword(s):

Mass Spectrometry ◽

Dna Binding ◽

Ubiquitin Ligase ◽

Terminal Region ◽

Cross Linking ◽

Chromatin Binding ◽

Protein Footprinting ◽

Intrinsically Disordered ◽

The Core ◽

Binding Surface

AbstractPolycomb Group (PcG) proteins regulate gene expression by modifying chromatin. A key PcG complex, Polycomb Repressive Complex 1 (PRC1), has two activities: a ubiquitin ligase activity for histone H2A, and a chromatin compacting activity. In Drosophila, the Posterior Sex Combs (PSC) subunit of PRC1 is central to both activities. The N-terminal homology region (HR) of PSC assembles into PRC1, including partnering with dRING to form the ubiquitin ligase for H2A. The intrinsically disordered C-terminal region of PSC (PSC-CTR) compacts chromatin, and inhibits chromatin remodeling and transcription in vitro. Both the PSC-HR and the PSC-CTR are essential in vivo. To understand how these two activities may be coordinated in PRC1, we used cross-linking mass spectrometry (XL-MS) to analyze the conformations of the PSC-CTR in PRC1 and how they change on binding DNA. XL-MS identifies interactions between the PSC-CTR and the core of PRC1, including between the PSC-CTR and PSC-HR. New contacts and overall more compacted PSC-CTR conformations are induced by DNA binding. Protein footprinting of accessible lysine residues in the PSC-CTR reveals an extended, bipartite candidate DNA/chromatin binding surface. Our data suggest a model in which DNA (or chromatin) follows a long path on the flexible PSC-CTR. Intramolecular interactions of the PSC-CTR detected by XL-MS can bring the high affinity DNA/chromatin binding region close to the core of PRC1 without disrupting the interface between the ubiquitin ligase and the nucleosome. Our approach may be applicable to understanding the global organization of other large IDRs that bind nucleic acids.HighlightsAn intrinsically disordered region (IDR) in Polycomb protein PSC compacts chromatinCross-linking mass spectrometry (XL-MS) was used to analyze topology of the PSC IDRProtein footprinting suggests a bipartite DNA binding surface in the PSC IDRA model for the DNA-driven organization of the PSC IDRCombining XL-MS and protein footprinting is a strategy to understand nucleic acid binding IDRsAbstract Figure

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The Fine Structure of Phloem Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119867 ◽

1985 ◽

Vol 43 ◽

pp. 632-635

Author(s):

James Cronshaw

Keyword(s):

Structural Studies ◽

High Concentration ◽

Long Distance ◽

Phloem Tissue ◽

Sieve Elements ◽

Long Distance Transport ◽

P Protein ◽

Companion Cells ◽

Electron Microscopical ◽

Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154780 ◽

1989 ◽

Vol 47 ◽

pp. 562-563

Author(s):

Gyeung Ho Kim ◽

Mehmet Sarikaya ◽

D. L. Milius ◽

I. A. Aksay

Keyword(s):

Thin Film ◽

Mechanical Properties ◽

Fracture Toughness ◽

Static Loading ◽

Carbon Deposition ◽

Full Density ◽

Unique Combination ◽

Strong Component ◽

Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

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Novel players fine-tune plant trade-offs

Essays in Biochemistry ◽

10.1042/bse0580083 ◽

2015 ◽

Vol 58 ◽

pp. 83-100 ◽

Cited By ~ 25

Author(s):

Selena Gimenez-Ibanez ◽

Marta Boter ◽

Roberto Solano

Keyword(s):

Ubiquitin Ligase ◽

Feedback Loop ◽

Molecular Level ◽

26S Proteasome ◽

Signalling Molecules ◽

Transcriptional Reprogramming ◽

Trade Offs ◽

Jaz Proteins ◽

Regulatory Feedback Loop ◽

Fine Tune

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.

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