scholarly journals Structural analysis of RIG-I-like receptors reveals ancient rules of engagement between diverse RNA helicases and TRIM ubiquitin ligases

2020 ◽  
Author(s):  
Kazuki Kato ◽  
Sadeem Ahmad ◽  
Zixiang Zhu ◽  
Janet M. Young ◽  
Xin Mu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Helicases ◽  
Animal Evolution ◽  
E3 Ligases ◽  
Cryo Electron Microscopy ◽  
Rna Biology ◽  
Evolutionarily Conserved ◽  
Tripartite Motif ◽  
Biochemical Analyses ◽  
Trim Proteins

AbstractRNA helicases and ubiquitin E3 ligases mediate many critical functions within cells, but their actions have been studied largely in distinct biological contexts. Here, we uncover evolutionarily conserved rules of engagement between RNA helicases and tripartite motif (TRIM) E3 ligases that lead to their functional coordination in vertebrate innate immunity. Using cryo-electron microscopy and biochemistry, we show that RIG-I-like receptors (RLRs), viral RNA receptors with helicase domains, interact with their cognate TRIM/TRIM-like E3 ligases through similar epitopes in the helicase domains. Their interactions are avidity-driven, restricting the actions of TRIM/TRIM-like proteins and consequent immune activation to RLR multimers. Mass-spectrometry and phylogeny-guided biochemical analyses further reveal that similar rules of engagement apply to diverse RNA helicases and TRIM/TRIM-like proteins. Our analyses thus reveal not only conserved substrates for TRIM proteins but also unexpectedly deep evolutionary connections between TRIM proteins and RNA helicases, thereby linking ubiquitin and RNA biology throughout animal evolution.

scholarly journals TRIM Proteins and Their Roles in Antiviral Host Defenses

2018 ◽  
Vol 5 (1) ◽  
pp. 385-405 ◽  
Author(s):  
Michiel van Gent ◽  
Konstantin M.J. Sparrer ◽  
Michaela U. Gack
Keyword(s):  
Host Defense ◽  
Host Immunity ◽  
Innate Immune ◽  
Host Defenses ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Cytokine Responses ◽  
Tripartite Motif ◽  
Trim Proteins

Tripartite motif (TRIM) proteins are a versatile family of ubiquitin E3 ligases involved in a multitude of cellular processes. Studies in recent years have demonstrated that many TRIM proteins play central roles in the host defense against viral infection. While some TRIM proteins directly antagonize distinct steps in the viral life cycle, others regulate signal transduction pathways induced by innate immune sensors, thereby modulating antiviral cytokine responses. Furthermore, TRIM proteins have been implicated in virus-induced autophagy and autophagy-mediated viral clearance. Given the important role of TRIM proteins in antiviral restriction, it is not surprising that several viruses have evolved effective maneuvers to neutralize the antiviral action of specific TRIM proteins. Here, we describe the major antiviral mechanisms of TRIM proteins as well as viral strategies to escape TRIM-mediated host immunity.

Functional interactions between ubiquitin E2 enzymes and TRIM proteins

2011 ◽  
Vol 434 (2) ◽  
pp. 309-319 ◽  
Author(s):  
Luisa M. Napolitano ◽  
Ellis G. Jaffray ◽  
Ronald T. Hay ◽  
Germana Meroni
Keyword(s):  
Coiled Coil ◽  
Specific Interactions ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Coiled Coil Region ◽  
Physiological Relevance ◽  
Tripartite Motif ◽  
E2 Enzymes ◽  
Specific Reactions ◽  
Trim Proteins

The TRIM (tripartite motif) family of proteins is characterized by the presence of the tripartite motif module, composed of a RING domain, one or two B-box domains and a coiled-coil region. TRIM proteins are involved in many cellular processes and represent the largest subfamily of RING-containing putative ubiquitin E3 ligases. Whereas their role as E3 ubiquitin ligases has been presumed, and in several cases established, little is known about their specific interactions with the ubiquitin-conjugating E2 enzymes or UBE2s. In the present paper, we report a thorough screening of interactions between the TRIM and UBE2 families. We found a general preference of the TRIM proteins for the D and E classes of UBE2 enzymes, but we also revealed very specific interactions between TRIM9 and UBE2G2, and TRIM32 and UBE2V1/2. Furthermore, we demonstrated that the TRIM E3 activity is only manifest with the UBE2 with which they interact. For most specific interactions, we could also observe subcellular co-localization of the TRIM involved and its cognate UBE2 enzyme, suggesting that the specific selection of TRIM–UBE2 pairs has physiological relevance. Our findings represent the basis for future studies on the specific reactions catalysed by the TRIM E3 ligases to determine the fate of their targets.

Abstract 218: The Role of Novel Tripartite Motif Proteins in Sarcolemmal Membrane Repair

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Liubov V Gushchina ◽  
Jenna Alloush ◽  
Sayak Bhattacharya ◽  
Zhaobin Xu ◽  
Eric X Beck ◽  
...  
Keyword(s):  
Membrane Damage ◽  
Coiled Coil ◽  
Cardiac Cells ◽  
Acute Injury ◽  
Membrane Repair ◽  
Repair Capacity ◽  
E3 Ligases ◽  
Tripartite Motif ◽  
Trim Proteins

Tripartite motif (TRIM) proteins are a superfamily of coiled-coil-containing RING E3 ligases that function in many cellular processes, particularly in membrane repair pathways. Mitsugumin 53 (MG53) also known as TRIM72, is primary expressed in skeletal muscle and heart. Our experimental data confirm that during membrane damage, MG53 translocates to the injury site and acts as a molecular glue to reseal the damage area. The role of MG53 in membrane repair has been demonstrated in both in vitro studies using molecular approaches and in vivo using rodent wild type and knockout models. Thus, our data indicate that recombinant human MG53 protein can be directly applied as a therapeutic agent to increase the membrane repair capacity of many cell types, including cardiomyocytes during acute injury or in chronic disease progression. However, the precise mechanism and potential partners by which MG53 executes its membrane repair function are not completely understood. On the basis of the global TRIM family protein alignment, we hypothesize that there are other TRIM proteins that, alone or together with MG53, may facilitate repair by targeting the site of an injury. Moreover, data from our lab demonstrated that MG53 and these TRIM proteins can form homo- and hetero-oligomeric assemblies due to the presence of the coiled-coil region in these proteins and, further, that this may be necessary for the active membrane resealing process. Using E. coli protein expression methodology we can generate and isolate new TRIM recombinant proteins and test if these protein complexes are effective when applied externally to cardiac and non-cardiac cells. These novel proteins will also be tested for their pharmacokinetic properties to determine their efficacy in both acute and chronic applications. Our studies should increase our knowledge of the mechanisms controlling cardiac membrane repair and also provide novel therapeutic targets.

scholarly journals Structural basis of Cullin-2 RING E3 ligase regulation by the COP9 signalosome

2018 ◽  
Author(s):  
Sarah V. Faull ◽  
Andy. M. C. Lau ◽  
Chloe Martens ◽  
Zainab Ahdash ◽  
Hugo Yebenes ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Activation Mechanism ◽  
Cop9 Signalosome ◽  
Structural Basis ◽  
Specific Substrate ◽  
Independent Manner ◽  
E3 Ligases ◽  
Cryo Electron Microscopy ◽  
Ring E3

SUMMARYCullin-Ring E3 Ligases (CRLs) regulate a multitude of cellular pathways through specific substrate receptors. The COP9 signalosome (CSN) deactivates CRLs by removing NEDD8 (N8) from activated Cullins. The structure of stable CSN-CRL can be used to understand this mechanism of regulation. Here we present the first structures of the neddylated and deneddylated CSN-CRL2 complexes by combining single particle cryo-electron microscopy (cryo-EM) with chemical cross-linking mass spectrometry (MS). These structures reveal a conserved mechanism of CSN activation, consisting of conformational clamping of the CRL2 substrate by CSN2/CSN4, release of the catalytic CSN5/CSN6 heterodimer and finally activation of the CSN5 deneddylation machinery. Using hydrogen deuterium exchange-MS we show that CRL2 binding and conformational activation of CSN5/CSN6 occur in a neddylation-independent manner. The presence of NEDD8 is required to activate the CSN5 active site. Overall, by synergising cryo-EM with MS, we identified novel sensory regions of the CSN that mediate its stepwise activation mechanism and provide a framework for better understanding the regulatory mechanism of other Cullin family members.One sentence summaryStructure and dynamics of the CSN-CRL2 complexes assessed by cryo-electron microscopy and structural mass spectrometry.

scholarly journals Tripartite motif-containing 3 (TRIM3) enhances ER signaling and confers tamoxifen resistance in breast cancer

Oncogenesis ◽  
2021 ◽  
Vol 10 (9) ◽  
Author(s):  
Runyi Ye ◽  
NiJiati AiErken ◽  
Xiaying Kuang ◽  
Huijuan Zeng ◽  
Nan Shao ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Tamoxifen Resistance ◽  
Clinical Problem ◽  
E3 Ligases ◽  
New Class ◽  
Tripartite Motif ◽  
Er Positive ◽  
And Function ◽  
Trim Proteins

AbstractTamoxifen resistance remains a clinical problem in estrogen receptor (ER)-positive breast cancer. SUMOylation of ERα enhances ERα-induced transcription activity. Tripartite motif-containing (TRIM) proteins are a new class of SUMO E3 ligases, which regulate the SUMOylation of proteins. However, the precise molecular mechanism and function of TRIM3 in SUMOylation and the response to tamoxifen remain unclear. In the present study, we observed that TRIM3 was dramatically overexpressed in breast cancer, which correlated with tamoxifen resistance. Furthermore, TRIM3 overexpression significantly correlated with poor survival of patients with ER+ breast cancer treated with tamoxifen. TRIM3 overexpression conferred cell survival and tumorigenesis, whereas knocking down of TRIM3 reduced these capabilities. Moreover, TRIM3, as a ubiquitin carrier protein 9 (UBC9) binding protein, promoted SUMO modification of estrogen receptor 1 (ESR1) and activated the ER pathway. Silencing UBC9 abolished the function of TRIM3 in regulating tamoxifen resistance. These results suggest TRIM3 as a novel biomarker for breast cancer therapy, indicating that inhibiting TRIM3 combined with tamoxifen might provide a potential treatment for breast cancer.

Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption

1984 ◽  
Vol 42 ◽  
pp. 232-233
Author(s):  
S.M. Geyer ◽  
C.L. Mendenhall ◽  
J.T. Hung ◽  
E.L. Cardell ◽  
R.L. Drake ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Malic Enzyme ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Mature Male ◽  
Treatment Groups ◽  
Malic Enzyme Activity ◽  
Biochemical Analyses

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.

New challenges to image processing posed by cryo-Electron microscopy of single particles

1991 ◽  
Vol 49 ◽  
pp. 422-423
Author(s):  
Joachim Frank
Keyword(s):  
Electron Microscopy ◽  
Phase Contrast ◽  
Particle Orientation ◽  
Single Particles ◽  
Contrast Transfer Function ◽  
Virtual Absence ◽  
Cryo Electron Microscopy ◽  
Spatial Frequencies ◽  
New Challenges ◽  
Particle Images

Compared with images of negatively stained single particle specimens, those obtained by cryo-electron microscopy have the following new features: (a) higher “signal” variability due to a higher variability of particle orientation; (b) reduced signal/noise ratio (S/N); (c) virtual absence of low-spatial-frequency information related to elastic scattering, due to the properties of the phase contrast transfer function (PCTF); and (d) reduced resolution due to the efforts of the microscopist to boost the PCTF at low spatial frequencies, in his attempt to obtain recognizable particle images.

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

Study of eukaryotic flagellar components by cryo-electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 98-101
Author(s):  
John M. Murray ◽  
Rob Ward
Keyword(s):  
Electron Microscopy ◽  
Primary Motion ◽  
Cryo Electron Microscopy ◽  
Cross Links ◽  
Cilia And Flagella

The eukaryotic flagellum is constructed from 11 parallel tubular elements arranged as 9 peripheral fibers (doublet microtubules) and 2 central fibers (singlet microtubules). The primary motion generating component has been found to be arranged as axially periodic “arms” bridging the adjacent doublets. The dynein, comprising the arms, has been isolated and characterized from several different cilia and flagella. Various radial and azimuthal cross-links stabilize the axially aligned microtubules, and probably play some role in controlling the form of the flagella beat cycle.

CRYO-Electron Microscopy of the Acto-Myosin-ATP Complex

1990 ◽  
Vol 48 (1) ◽  
pp. 248-249
Author(s):  
John Trinickt ◽  
Howard White
Keyword(s):  
Electron Microscopy ◽  
Atp Hydrolysis ◽  
Myosin Head ◽  
Bound State ◽  
Cross Linking ◽  
Weakly Bound ◽  
Cryo Electron Microscopy ◽  
Myosin Subfragment 1 ◽  
Attached State ◽  
High Fraction

The primary force of muscle contraction is thought to involve a change in the myosin head whilst attached to actin, the energy coming from ATP hydrolysis. This change in attached state could either be a conformational change in the head or an alteration in the binding angle made with actin. A considerable amount is known about one bound state, the so-called strongly attached state, which occurs in the presence of ADP or in the absence of nucleotide. In this state, which probably corresponds to the last attached state of the force-producing cycle, the angle between the long axis myosin head and the actin filament is roughly 45°. Details of other attached states before and during power production have been difficult to obtain because, even at very high protein concentration, the complex is almost completely dissociated by ATP. Electron micrographs of the complex in the presence of ATP have therefore been obtained only after chemically cross-linking myosin subfragment-1 (S1) to actin filaments to prevent dissociation. But it is unclear then whether the variability in attachment angle observed is due merely to the cross-link acting as a hinge.We have recently found low ionic-strength conditions under which, without resorting to cross-linking, a high fraction of S1 is bound to actin during steady state ATP hydrolysis. The structure of this complex is being studied by cryo-electron microscopy of hydrated specimens. Most advantages of frozen specimens over ambient temperature methods such as negative staining have already been documented. These include improved preservation and fixation rates and the ability to observe protein directly rather than a surrounding stain envelope. In the present experiments, hydrated specimens have the additional benefit that it is feasible to use protein concentrations roughly two orders of magnitude higher than in conventional specimens, thereby reducing dissociation of weakly bound complexes.

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