scholarly journals Allosteric coupling between α-rings of the 20S proteasome

2019 ◽  
Author(s):  
Zanlin Yu ◽  
Yadong Yu ◽  
Feng Wang ◽  
Alexander G. Myasnikov ◽  
Philip Coffino ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Cooperative Binding ◽  
20S Proteasome ◽  
Allosteric Coupling ◽  
In Cells

AbstractThe proteasomal machinery performs essential regulated protein degradation in eukaryotes. Classic proteasomes are symmetric, with a regulatory ATPase docked at each end of the cylindrical 20S. Asymmetric complexes are also present in cells, either with a single ATPase or with an ATPase and non-ATPase at two opposite ends. The mechanism that populates these different proteasomal complexes is unknown. Using archaea homologs, we constructed asymmetric forms of proteasomes. We demonstrate that the gate conformation of two opposite ends of 20S are coupled: binding one ATPase opens a gate locally, and also the remote opposite gate allosterically. Such allosteric coupling leads to cooperative binding of proteasomal ATPases to 20S, and promotes formation of proteasomes symmetrically configured with two identical ATPases. It may also promote formation of asymmetric complexes with an ATPase and a non-ATPase at opposite ends. We propose that in eukaryotes a similar mechanism regulates the composition of the proteasomal population.

scholarly journals Allosteric coupling between α-rings of the 20S proteasome

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zanlin Yu ◽  
Yadong Yu ◽  
Feng Wang ◽  
Alexander G. Myasnikov ◽  
Philip Coffino ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Cooperative Binding ◽  
20S Proteasome ◽  
Allosteric Coupling ◽  
In Cells

Abstract Proteasomal machinery performs essential regulated protein degradation in eukaryotes. Classic proteasomes are symmetric, with a regulatory ATPase docked at each end of the cylindrical 20S. Asymmetric complexes are also present in cells, either with a single ATPase or with an ATPase and non-ATPase at two opposite ends. The mechanism that populates these different proteasomal complexes is unknown. Using archaea homologs, we construct asymmetric forms of proteasomes. We demonstrate that the gate conformation of the two opposite ends of 20S are coupled: binding one ATPase opens a gate locally, and also opens the opposite gate allosterically. Such allosteric coupling leads to cooperative binding of proteasomal ATPases to 20S and promotes formation of proteasomes symmetrically configured with two identical ATPases. It may also promote formation of asymmetric complexes with an ATPase and a non-ATPase at opposite ends. We propose that in eukaryotes a similar mechanism regulates the composition of the proteasomal population.

scholarly journals Observing Protein Degradation by the PAN-20S Proteasome by Time-Resolved Neutron Scattering

2020 ◽  
Vol 119 (2) ◽  
pp. 375-388 ◽  
Author(s):  
Emilie Mahieu ◽  
Jacques Covès ◽  
Georg Krüger ◽  
Anne Martel ◽  
Martine Moulin ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Protein Degradation ◽  
20S Proteasome ◽  
Time Resolved

scholarly journals Involvement of the Ubiquitin-Proteasome System in the Formation of Experimental Postsurgical Peritoneal Adhesions

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Clara Di Filippo ◽  
Pasquale Petronella ◽  
Fulvio Freda ◽  
Marco Scorzelli ◽  
Marco Ferretti ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Ubiquitin Proteasome System ◽  
20S Proteasome ◽  
Intracellular Protein ◽  
Peritoneal Adhesions ◽  
Proteasome Subunit ◽  
Peritoneal Tissue ◽  
Intracellular Protein Degradation ◽  
Ubiquitin Proteasome

We investigated the Ubiquitin-Proteasome System (UPS), major nonlysosomal intracellular protein degradation system, in the genesis of experimental postsurgical peritoneal adhesions. We assayed the levels of UPS within the adhered tissue along with the development of peritoneal adhesions and used the specific UPS inhibitor bortezomib in order to assess the effect of the UPS blockade on the peritoneal adhesions. We found a number of severe postsurgical peritoneal adhesions at day 5 after surgery increasing until day 10. In the adhered tissue an increased values of ubiquitin and the 20S proteasome subunit, NFkB, IL-6, TNF-αand decreased values of IkB-beta were found. In contrast, bortezomib-treated rats showed a decreased number of peritoneal adhesions, decreased values of ubiquitin and the 20S proteasome, NFkB, IL-6, TNF-α, and increased levels of IkB-beta in the adhered peritoneal tissue. The UPS system, therefore, is primarily involved in the formation of post-surgical peritoneal adhesions in rats.

scholarly journals Tau protein degradation is catalyzed by the ATP/ubiquitin-independent 20S proteasome under normal cell conditions

2010 ◽  
Vol 500 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Tilman Grune ◽  
Diana Botzen ◽  
Martina Engels ◽  
Peter Voss ◽  
Barbara Kaiser ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Tau Protein ◽  
Normal Cell ◽  
20S Proteasome

scholarly journals Ubiquitin-independent protein degradation in proteasomes

2018 ◽  
Vol 64 (2) ◽  
pp. 134-148 ◽  
Author(s):  
O.A. Buneeva ◽  
A.E. Medvedev
Keyword(s):  
Protein Degradation ◽  
Mammalian Cells ◽  
Intrinsically Disordered Proteins ◽  
Amino Acid Sequences ◽  
Disordered Proteins ◽  
20S Proteasome ◽  
Independent Manner ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Independent Protein

Proteasomes are large supramolecular protein complexes present in all prokaryotic and eukaryotic cells, where they perform targeted degradation of intracellular proteins. Until recently, it was generally accepted that prior proteolytic degradation in proteasomes the proteins had to be targeted by ubiquitination: the ATP-dependent addition of (typically four sequential) residues of the low-molecular ubiquitin protein, involving the ubiquitin-activating enzyme, ubiquitin-conjugating enzyme and ubiquitin ligase. The cytoplasm and nucleoplasm proteins labeled in this way are then digested in 26S proteasomes. However, in recent years it has become increasingly clear that using this route the cell eliminates only a part of unwanted proteins. Many proteins can be cleaved by the 20S proteasome in an ATP-independent manner and without previous ubiquitination. Ubiquitin-independent protein degradation in proteasomes is a relatively new area of studies of the role of the ubiquitin-proteasome system. However, recent data obtained in this direction already correct existing concepts about proteasomal degradation of proteins and its regulation. Ubiquitin-independent proteasome degradation needs the main structural precondition in proteins: the presence of unstructured regions in the amino acid sequences that provide interaction with the proteasome. Taking into consideration that in humans almost half of all genes encode proteins that contain a certain proportion of intrinsically disordered regions, it appears that the list of proteins undergoing ubiquitin-independent degradation will demonstrate further increase. Since 26S of proteasomes account for only 30% of the total proteasome content in mammalian cells, most of the proteasomes exist in the form of 20S complexes. The latter suggests that ubiquitin-independent proteolysis performed by the 20S proteasome is a natural process of removing damaged proteins from the cell and maintaining a constant level of intrinsically disordered proteins. In this case, the functional overload of proteasomes in aging and/or other types of pathological processes, if it is not accompanied by triggering more radical mechanisms for the elimination of damaged proteins, organelles and whole cells, has the most serious consequences for the whole organism.

scholarly journals Cooperative Binding of the Cationic Porphyrin Tris-T4 Enhances Catalytic Activity of 20S Proteasome Unveiling a Complex Distribution of Functional States

2020 ◽  
Vol 21 (19) ◽  
pp. 7190
Author(s):  
Anna Maria Santoro ◽  
Alessandro D’Urso ◽  
Alessandra Cunsolo ◽  
Danilo Milardi ◽  
Roberto Purrello ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Interaction Model ◽  
In Silico Analysis ◽  
Cooperative Binding ◽  
20S Proteasome ◽  
Conformational Effects ◽  
Dynamic View ◽  
Functional States ◽  
New Generation ◽  
Substrate Hydrolysis

The present study provides new evidence that cationic porphyrins may be considered as tunable platforms to interfere with the structural “key code” present on the 20S proteasome α-rings and, by consequence, with its catalytic activity. Here, we describe the functional and conformational effects on the 20S proteasome induced by the cooperative binding of the tri-cationic 5-(phenyl)-10,15,20-(tri N-methyl-4-pyridyl) porphyrin (Tris-T4). Our integrated kinetic, NMR, and in silico analysis allowed us to disclose a complex effect on the 20S catalytic activity depending on substrate/porphyrin concentration. The analysis of the kinetic data shows that Tris-T4 shifts the relative populations of the multiple interconverting 20S proteasome conformations leading to an increase in substrate hydrolysis by an allosteric pathway. Based on our Tris-T4/h20S interaction model, Tris-T4 is able to affect gating dynamics and substrate hydrolysis by binding to an array of negatively charged and hydrophobic residues present on the protein surface involved in the 20S molecular activation by the regulatory proteins (RPs). Accordingly, despite the fact that Tris-T4 also binds to the α3ΔN mutant, allosteric modulation is not observed since the molecular mechanism connecting gate dynamics with substrate hydrolysis is impaired. We envisage that the dynamic view of the 20S conformational equilibria, activated through cooperative Tris-T4 binding, may work as a simplified model for a better understanding of the intricate network of 20S conformational/functional states that may be mobilized by exogenous ligands, paving the way for the development of a new generation of proteasome allosteric modulators.

scholarly journals SEL-10 Is an Inhibitor of Notch Signaling That Targets Notch for Ubiquitin-Mediated Protein Degradation

2001 ◽  
Vol 21 (21) ◽  
pp. 7403-7415 ◽  
Author(s):  
Guangyu Wu ◽  
Svetlana Lyapina ◽  
Indranil Das ◽  
Jinhe Li ◽  
Mark Gurney ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Protein Degradation ◽  
Notch Receptor ◽  
Dominant Negative ◽  
Intracellular Domain ◽  
Notch Receptors ◽  
Intracellular Domains ◽  
Wd40 Repeats ◽  
In Cells

ABSTRACT Notch receptors and their ligands play important roles in both normal animal development and pathogenesis. We show here that the F-box/WD40 repeat protein SEL-10 negatively regulates Notch receptor activity by targeting the intracellular domain of Notch receptors for ubiquitin-mediated protein degradation. Blocking of endogenous SEL-10 activity was done by expression of a dominant-negative form containing only the WD40 repeats. In the case of Notch1, this block leads to an increase in Notch signaling stimulated by either an activated form of the Notch1 receptor or Jagged1-induced signaling through Notch1. Expression of dominant-negative SEL-10 leads to stabilization of the intracellular domain of Notch1. The Notch4 intracellular domain bound to SEL-10, but its activity was not increased as a result of dominant-negative SEL-10 expression. SEL-10 bound Notch4 via the WD40 repeats and bound preferentially to a phosphorylated form of Notch4 in cells. We mapped the region of Notch4 essential for SEL-10 binding to the C-terminal region downstream of the ankyrin repeats. When this C-terminal fragment of Notch4 was expressed in cells, it was highly labile but could be stabilized by the expression of dominant-negative SEL-10. Ubiquitination of Notch1 and Notch4 intracellular domains in vitro was dependent on SEL-10. Although SEL-10 interacts with the intracellular domains of both Notch1 and Notch4, these proteins respond differently to interference with SEL-10 function. Thus, SEL-10 functions to promote the ubiquitination of Notch proteins; however, the fates of these proteins may differ.

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