scholarly journals Function of the p97–Ufd1–Npl4 complex in retrotranslocation from the ER to the cytosol

2003 ◽  
Vol 162 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Yihong Ye ◽  
Hemmo H. Meyer ◽  
Tom A. Rapoport
Keyword(s):  
Atp Hydrolysis ◽  
Bound State ◽  
Polyubiquitin Chain ◽  
Polyubiquitin Chains ◽  
Evolutionarily Conserved ◽  
The Family ◽  
Complex Functions ◽  
Ubiquitin Binding ◽  
Subsequent Degradation ◽  
Er Membrane

Amember of the family of ATPases associated with diverse cellular activities, called p97 in mammals and Cdc48 in yeast, associates with the cofactor Ufd1–Npl4 to move polyubiquitinated polypeptides from the endoplasmic reticulum (ER) membrane into the cytosol for their subsequent degradation by the proteasome. Here, we have studied the mechanism by which the p97–Ufd1–Npl4 complex functions in this retrotranslocation pathway. Substrate binding occurs when the first ATPase domain of p97 (D1 domain) is in its nucleotide-bound state, an interaction that also requires an association of p97 with the membrane through its NH2-terminal domain. The two ATPase domains (D1 and D2) of p97 appear to alternate in ATP hydrolysis, which is essential for the movement of polypeptides from the ER membrane into the cytosol. The ATPase itself can interact with nonmodified polypeptide substrates as they emerge from the ER membrane. Polyubiquitin chains linked by lysine 48 are recognized in a synergistic manner by both p97 and an evolutionarily conserved ubiquitin-binding site at the NH2 terminus of Ufd1. We propose a dual recognition model in which the ATPase complex binds both a nonmodified segment of the substrate and the attached polyubiquitin chain; polyubiquitin binding may activate the ATPase p97 to pull the polypeptide substrate out of the membrane.

scholarly journals A novel polyubiquitin chain linkage formed by viral Ubiquitin prevents cleavage by deubiquitinating enzymes

2019 ◽  
Author(s):  
Hitendra Negi ◽  
Pothula Puroshotham Reddy ◽  
Chhaya Patole ◽  
Ranabir Das
Keyword(s):  
Biochemical Properties ◽  
Autographa Californica ◽  
Polyubiquitin Chain ◽  
Deubiquitinating Enzymes ◽  
Polyubiquitin Chains ◽  
Antiviral Responses ◽  
Binding Domains ◽  
Central Helix ◽  
Ubiquitin Binding ◽  
The Stability

ABSTRACTThe Baculoviridae family of viruses encode a viral Ubiquitin gene. Although the viral Ubiquitin is homologous to eukaryotic Ubiquitin (Ub), preservation of this gene in the viral genome indicates a unique function that is absent in the host eukaryotic Ub. We report the structural, biophysical, and biochemical properties of the viral Ubiquitin from Autographa Californica Multiple Nucleo-Polyhedrosis Virus (AcMNPV). The structure of viral Ubiquitin (vUb) differs from Ub in the packing of the central helix α1 to the beta-sheet of the β-grasp fold. Consequently, the stability of the fold is lower in vUb compared to Ub. However, the surface properties, ubiquitination activity, and the interaction with Ubiquitin binding domains are similar between vUb and Ub. Interestingly, vUb forms atypical polyubiquitin chain linked by lysine at the 54th position (K54). The K54-linked polyubiquitin chains are neither effectively cleaved by deubiquitinating enzymes, nor are they targeted by proteasomal degradation. We propose that modification of proteins with the viral Ubiquitin is a mechanism to counter the host antiviral responses.

Orchestra for assembly and fate of polyubiquitin chains

2005 ◽  
Vol 41 ◽  
pp. 1-14 ◽  
Author(s):  
Kuhlbrodt Kirsten ◽  
Mouysset Julien ◽  
Hoppe Thorsten
Keyword(s):  
Protein Degradation ◽  
Ubiquitin Ligase ◽  
Chain Elongation ◽  
Polyubiquitin Chain ◽  
Ubiquitin Chain ◽  
Polyubiquitin Chains ◽  
Intracellular Signals ◽  
Ubiquitin Binding ◽  
Ubiquitin Ligase E3 ◽  
Ubiquitin Conjugating Enzyme

Selective protein degradation by the 26 S proteasome usually requires a polyubiquitin chain attached to the protein substrate by three classes of enzymes: a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2), and a ubiquitin ligase (E3). This reaction can produce different polyubiquitin chains that, depending on size and linkage type, can provide distinct intracellular signals. Interestingly, polyubiquitination is sometimes regulated by additional conjugation factors, called E4s (polyubiquitin chain conjugation factors). Yeast UFD2 (ubiquitin fusion degradation protein-2), the first E4 to be described, binds to the ubiquitin moieties of preformed conjugates and catalyses ubiquitin-chain elongation together with E1, E2, and E3. Recent studies have illustrated that the E4 enzyme UFD2 co-operates with an orchestra of ubiquitin-binding factors in an escort pathway to transfer and deliver polyubiquitinated substrates to the 26 S proteasome. Here we propose a model in which E4-dependent polyubiquitination pathways are modulated by different ubiquitin-binding proteins, using ataxin-3 as an example.

scholarly journals A novel polyubiquitin chain linkage formed by viral Ubiquitin is resistant to host deubiquitinating enzymes

2020 ◽  
Vol 477 (12) ◽  
pp. 2193-2219
Author(s):  
Hitendra Negi ◽  
Pothula Purushotham Reddy ◽  
Vineeth Vengayil ◽  
Chhaya Patole ◽  
Sunil Laxman ◽  
...  
Keyword(s):  
Viral Genome ◽  
Viral Proteins ◽  
Biochemical Properties ◽  
Autographa Californica ◽  
Polyubiquitin Chain ◽  
Deubiquitinating Enzymes ◽  
Polyubiquitin Chains ◽  
Binding Domains ◽  
Central Helix ◽  
Ubiquitin Binding

The Baculoviridae family of viruses encode a viral Ubiquitin (vUb) gene. Though the vUb is homologous to the host eukaryotic Ubiquitin (Ub), its preservation in the viral genome indicates unique functions that are not compensated by the host Ub. We report the structural, biophysical, and biochemical properties of the vUb from Autographa californica multiple nucleo-polyhedrosis virus (AcMNPV). The packing of central helix α1 to the beta-sheet β1–β5 is different between vUb and Ub. Consequently, its stability is lower compared with Ub. However, the surface properties, ubiquitination activity, and the interaction with Ubiquitin-binding domains are similar between vUb and Ub. Interestingly, vUb forms atypical polyubiquitin chain linked by lysine at the 54th position (K54), and the deubiquitinating enzymes are ineffective against the K54-linked polyubiquitin chains. We propose that the modification of host/viral proteins with the K54-linked chains is an effective way selected by the virus to protect the vUb signal from host DeUbiquitinases.

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.

Phylogeny accurately predicts behaviour in Indian Ocean Clitaetra spiders (Araneae:Nephilidae)

2009 ◽  
Vol 23 (3) ◽  
pp. 193 ◽  
Author(s):  
Matjaž Kuntner ◽  
Ingi Agnarsson
Keyword(s):  
South Africa ◽  
Phylogenetic Analysis ◽  
Indian Ocean ◽  
Species Level ◽  
Web Architecture ◽  
Evolutionarily Conserved ◽  
The Family ◽  
Behavioural Biology

Phylogenies are underutilised, powerful predictors of traits in unstudied species. We tested phylogenetic predictions of web-related behaviour in Clitaetra Simon, 1889, an Afro-Indian spider genus of the family Nephilidae. Clitaetra is phylogenetically sister to all other nephilids and thus important for understanding ancestral traits. Behavioural information on Clitaetra has been limited to only C. irenae Kuntner, 2006 from South Africa which constructs ladder webs. A resolved species-level phylogeny unambiguously optimised Clitaetra behavioural biology and predicted web traits in five unstudied species and a uniform intrageneric nephilid web biology. We tested these predictions by studying the ecology and web biology of C. perroti Simon, 1894 on Madagascar and C. episinoides Simon, 1889 on Mayotte. We confirm predicted arboricolous web architecture in these species. The expected ontogenetic allometric transition from orbs in juveniles to elongate ladder webs in adults was statistically significant in C. perroti, whereas marginally not significant in C. episinoides. We demonstrate the persistence of the temporary spiral in finished Clitaetra webs. A morphological and behavioural phylogenetic analysis resulted in unchanged topology and persisting unambiguous behavioural synapomorphies. Our results support the homology of Clitaetra hub reinforcement with the nephilid hub-cup. In Clitaetra, behaviour was highly predictable and remained consistent with new observations. Our results confirm that nephilid web biology is evolutionarily conserved within genera.

scholarly journals Structural insights into the mechanism of the DEAH-box RNA helicase Prp43

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Marcel J Tauchert ◽  
Jean-Baptiste Fourmann ◽  
Reinhard Lührmann ◽  
Ralf Ficner
Keyword(s):  
Conformational Changes ◽  
Bound States ◽  
Rna Binding ◽  
Atp Hydrolysis ◽  
Bound State ◽  
Rna Helicases ◽  
Large Rearrangements ◽  
Rna Complex ◽  
Structural Insights ◽  
Terminal Domains

The DEAH-box helicase Prp43 is a key player in pre-mRNA splicing as well as the maturation of rRNAs. The exact modus operandi of Prp43 and of all other spliceosomal DEAH-box RNA helicases is still elusive. Here, we report crystal structures of Prp43 complexes in different functional states and the analysis of structure-based mutants providing insights into the unwinding and loading mechanism of RNAs. The Prp43•ATP-analog•RNA complex shows the localization of the RNA inside a tunnel formed by the two RecA-like and C-terminal domains. In the ATP-bound state this tunnel can be transformed into a groove prone for RNA binding by large rearrangements of the C-terminal domains. Several conformational changes between the ATP- and ADP-bound states explain the coupling of ATP hydrolysis to RNA translocation, mainly mediated by a β-turn of the RecA1 domain containing the newly identified RF motif. This mechanism is clearly different to those of other RNA helicases.

scholarly journals Intermediate step of cohesin’s ATPase cycle allows cohesin to entrap DNA

2018 ◽  
Vol 115 (39) ◽  
pp. 9732-9737 ◽  
Author(s):  
Gamze Ö. Çamdere ◽  
Kristian K. Carlborg ◽  
Douglas Koshland
Keyword(s):  
Atp Hydrolysis ◽  
Intermediate Step ◽  
Mutant Form ◽  
In Vitro Reconstitution ◽  
Chromatid Cohesion ◽  
The Family ◽  
Structural Maintenance Of Chromosomes ◽  
Dna Substrate

Cohesin is a four-subunit ATPase in the family of structural maintenance of chromosomes (SMC). Cohesin promotes sister chromatid cohesion, chromosome condensation, DNA repair, and transcription regulation. Cohesin performs these functions as a DNA tether and potentially a DNA-based motor. At least one of its DNA binding activities involves entrapment of DNA within a lumen formed by its subunits. This activity can be reconstituted in vitro by incubating cohesin with DNA, ATP, and cohesin loader. Previously we showed that a mutant form of cohesin (DE-cohesin) possesses the ability to bind and tether DNA in vivo. Using in vitro reconstitution assays, we show that DE-cohesin can form stable complexes with DNA without ATP hydrolysis. We show that wild-type cohesin with ADP aluminum fluoride (cohesinADP/AlFx) can also form stable cohesin–DNA complexes. These results suggest that an intermediate nucleotide state of cohesin, likely cohesinADP-Pi, is capable of initially dissociating one interface between cohesin subunits to allow DNA entry into a cohesin lumen and subsequently interacting with the bound DNA to stabilize DNA entrapment. We also show that cohesinADP/AlFx binding to DNA is enhanced by cohesin loader, suggesting a function for loader other than stimulating the ATPase. Finally, we show that loader remains stably bound to cohesinADP/AlFx after DNA entrapment, potentially revealing a function for loader in tethering the second DNA substrate. These results provide important clues on how SMC complexes like cohesin can function as both DNA tethers and motors.

scholarly journals Specific Molecular Chaperone Interactions and an ATP-dependent Conformational Change Are Required during Posttranslational Protein Translocation into the Yeast ER

1998 ◽  
Vol 9 (12) ◽  
pp. 3533-3545 ◽  
Author(s):  
Amie J. McClellan ◽  
James B. Endres ◽  
Joseph P. Vogel ◽  
Debra Palazzi ◽  
Mark D. Rose ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Conformational Change ◽  
Molecular Chaperone ◽  
Atp Hydrolysis ◽  
Protein Translocation ◽  
Wild Type ◽  
J Domain ◽  
Chaperone Interactions ◽  
Dependent Interaction ◽  
Er Membrane

The posttranslational translocation of proteins across the endoplasmic reticulum (ER) membrane in yeast requires ATP hydrolysis and the action of hsc70s (DnaK homologues) and DnaJ homologues in both the cytosol and ER lumen. Although the cytosolic hsc70 (Ssa1p) and the ER lumenal hsc70 (BiP) are homologous, they cannot substitute for one another, possibly because they interact with specific DnaJ homologues on each side of the ER membrane. To investigate this possibility, we purified Ssa1p, BiP, Ydj1p (a cytosolic DnaJ homologue), and a GST–63Jp fusion protein containing the lumenal DnaJ region of Sec63p. We observed that BiP, but not Ssa1p, is able to associate with GST–63Jp and that Ydj1p stimulates the ATPase activity of Ssa1p up to 10-fold but increases the ATPase activity of BiP by <2-fold. In addition, Ydj1p and ATP trigger the release of an unfolded polypeptide from Ssa1p but not from BiP. To understand further how BiP drives protein translocation, we purified four dominant lethal mutants of BiP. We discovered that each mutant is defective for ATP hydrolysis, fails to undergo an ATP-dependent conformational change, and cannot interact with GST–63Jp. Measurements of protein translocation into reconstituted proteoliposomes indicate that the mutants inhibit translocation even in the presence of wild-type BiP. We conclude that a conformation- and ATP-dependent interaction of BiP with the J domain of Sec63p is essential for protein translocation and that the specificity of hsc70 action is dictated by their DnaJ partners.

scholarly journals Focus on the Role of NLRP3 Inflammasome in Diseases

2020 ◽  
Vol 21 (12) ◽  
pp. 4223 ◽  
Author(s):  
Roberta Fusco ◽  
Rosalba Siracusa ◽  
Tiziana Genovese ◽  
Salvatore Cuzzocrea ◽  
Rosanna Di Paola
Keyword(s):  
Immune System ◽  
Nlrp3 Inflammasome ◽  
Neurologic Disorders ◽  
Evolutionarily Conserved ◽  
The Family ◽  
Bowel Diseases ◽  
Protective Reaction ◽  
Inflammatory Bowel

Inflammation is a protective reaction activated in response to detrimental stimuli, such as dead cells, irritants or pathogens, by the evolutionarily conserved immune system and is regulated by the host. The inflammasomes are recognized as innate immune system sensors and receptors that manage the activation of caspase-1 and stimulate inflammation response. They have been associated with several inflammatory disorders. The NLRP3 inflammasome is the most well characterized. It is so called because NLRP3 belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent evidence has greatly improved our understanding of the mechanisms by which the NLRP3 inflammasome is activated. Additionally, increasing data in animal models, supported by human studies, strongly implicate the involvement of the inflammasome in the initiation or progression of disorders with a high impact on public health, such as metabolic pathologies (obesity, type 2 diabetes, atherosclerosis), cardiovascular diseases (ischemic and non-ischemic heart disease), inflammatory issues (liver diseases, inflammatory bowel diseases, gut microbiome, rheumatoid arthritis) and neurologic disorders (Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis and other neurological disorders), compared to other molecular platforms. This review will provide a focus on the available knowledge about the NLRP3 inflammasome role in these pathologies and describe the balance between the activation of the harmful and beneficial inflammasome so that new therapies can be created for patients with these diseases.

scholarly journals Structural Basis of Ubiquitin Recognition by the Ubiquitin-associated (UBA) Domain of the Ubiquitin Ligase EDD

2007 ◽  
Vol 282 (49) ◽  
pp. 35787-35795 ◽  
Author(s):  
Guennadi Kozlov ◽  
Long Nguyen ◽  
Tong Lin ◽  
Gregory De Crescenzo ◽  
Morag Park ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Site Directed Mutagenesis ◽  
Structural Basis ◽  
Titration Calorimetry ◽  
Polyubiquitin Chains ◽  
C Terminus ◽  
Damage Repair ◽  
The Family ◽  
Uba Domain ◽  
Ordered Water

EDD (or HYD) is an E3 ubiquitin ligase in the family of HECT (homologous to E6-AP C terminus) ligases. EDD contains an N-terminal ubiquitin-associated (UBA) domain, which is present in a variety of proteins involved in ubiquitin-mediated processes. Here, we use isothermal titration calorimetry (ITC), NMR titrations, and pull-down assays to show that the EDD UBA domain binds ubiquitin. The 1.85Å crystal structure of the complex with ubiquitin reveals the structural basis of ubiquitin recognition by UBA helices α1 and α3. The structure shows a larger number of intermolecular hydrogen bonds than observed in previous UBA/ubiquitin complexes. Two of these involve ordered water molecules. The functional importance of residues at the UBA/ubiquitin interface was confirmed using site-directed mutagenesis. Surface plasmon resonance (SPR) measurements show that the EDD UBA domain does not have a strong preference for polyubiquitin chains over monoubiquitin. This suggests that EDD binds to monoubiquitinated proteins, which is consistent with its involvement in DNA damage repair pathways.

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