scholarly journals Structure of Vps4 with circular peptides and implications for translocation of two polypeptide chains by AAA+ ATPases

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Han Han ◽  
James M Fulcher ◽  
Venkata P Dandey ◽  
Janet H Iwasa ◽  
Wesley I Sundquist ◽  
...  
Keyword(s):  
Cyclic Peptide ◽  
Peptide Ligands ◽  
General Mechanism ◽  
Single Chain ◽  
Aaa Atpase ◽  
Protein Substrates ◽  
Multiple Structures ◽  
Polypeptide Chains ◽  
Aaa Atpases ◽  
Hairpin Conformation

Many AAA+ ATPases form hexamers that unfold protein substrates by translocating them through their central pore. Multiple structures have shown how a helical assembly of subunits binds a single strand of substrate, and indicate that translocation results from the ATP-driven movement of subunits from one end of the helical assembly to the other end. To understand how more complex substrates are bound and translocated, we demonstrated that linear and cyclic versions of peptides bind to the S. cerevisiae AAA+ ATPase Vps4 with similar affinities, and determined cryo-EM structures of cyclic peptide complexes. The peptides bind in a hairpin conformation, with one primary strand equivalent to the single chain peptide ligands, while the second strand returns through the translocation pore without making intimate contacts with Vps4. These observations indicate a general mechanism by which AAA+ ATPases may translocate a variety of substrates that include extended chains, hairpins, and crosslinked polypeptide chains.

scholarly journals Structure and mechanism of the ESCRT pathway AAA+ ATPase Vps4

2019 ◽  
Vol 47 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Han Han ◽  
Christopher P. Hill
Keyword(s):  
Cell Biology ◽  
Cellular Membrane ◽  
Structural Features ◽  
Transport Pathways ◽  
Endosomal Sorting ◽  
Aaa Atpase ◽  
Protein Substrates ◽  
Membrane Fission ◽  
Aaa Atpases ◽  
Equivalent Mechanism

Abstract The progression of ESCRT (Endosomal Sorting Complexes Required for Transport) pathways, which mediate numerous cellular membrane fission events, is driven by the enzyme Vps4. Understanding of Vps4 mechanism is, therefore, of fundamental importance in its own right and, moreover, it is highly relevant to the understanding of many related AAA+ ATPases that function in multiple facets of cell biology. Vps4 unfolds its ESCRT-III protein substrates by translocating them through its central hexameric pore, thereby driving membrane fission and recycling of ESCRT-III subunits. This mini-review focuses on recent advances in Vps4 structure and mechanism, including ideas about how Vps4 translocates and unfolds ESCRT-III subunits. Related AAA+ ATPases that share structural features with Vps4 and likely utilize an equivalent mechanism are also discussed.

scholarly journals Phage-Display Based Discovery and Characterization of Peptide Ligands against WDR5

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1225
Author(s):  
Jiawen Cao ◽  
Tiantian Fan ◽  
Yanlian Li ◽  
Zhiyan Du ◽  
Lin Chen ◽  
...  
Keyword(s):  
Phage Display ◽  
Cyclic Peptide ◽  
Protein Complexes ◽  
Peptide Ligands ◽  
Phage Library ◽  
Cancer Drug ◽  
Protein Protein Interaction ◽  
Phage Display Technique ◽  
Peptide Mimic ◽  
Human Proteins

WD40 is a ubiquitous domain presented in at least 361 human proteins and acts as scaffold to form protein complexes. Among them, WDR5 protein is an important mediator in several protein complexes to exert its functions in histone modification and chromatin remodeling. Therefore, it was considered as a promising epigenetic target involving in anti-cancer drug development. In view of the protein–protein interaction nature of WDR5, we initialized a campaign to discover new peptide-mimic inhibitors of WDR5. In current study, we utilized the phage display technique and screened with a disulfide-based cyclic peptide phage library. Five rounds of biopanning were performed and isolated clones were sequenced. By analyzing the sequences, total five peptides were synthesized for binding assay. The four peptides are shown to have the moderate binding affinity. Finally, the detailed binding interactions were revealed by solving a WDR5-peptide cocrystal structure.

scholarly journals The AAA+ ATPase p97, a cellular multitool

2017 ◽  
Vol 474 (17) ◽  
pp. 2953-2976 ◽  
Author(s):  
Lasse Stach ◽  
Paul S. Freemont
Keyword(s):  
Atp Hydrolysis ◽  
Current Status ◽  
Cellular Functions ◽  
Aaa Atpase ◽  
Cellular Processes ◽  
Proteotoxic Stress ◽  
Binding Domains ◽  
Wide Range ◽  
Aaa Atpases ◽  
Substrate Proteins

The AAA+ (ATPases associated with diverse cellular activities) ATPase p97 is essential to a wide range of cellular functions, including endoplasmic reticulum-associated degradation, membrane fusion, NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation and chromatin-associated processes, which are regulated by ubiquitination. p97 acts downstream from ubiquitin signaling events and utilizes the energy from ATP hydrolysis to extract its substrate proteins from cellular structures or multiprotein complexes. A multitude of p97 cofactors have evolved which are essential to p97 function. Ubiquitin-interacting domains and p97-binding domains combine to form bi-functional cofactors, whose complexes with p97 enable the enzyme to interact with a wide range of ubiquitinated substrates. A set of mutations in p97 have been shown to cause the multisystem proteinopathy inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia. In addition, p97 inhibition has been identified as a promising approach to provoke proteotoxic stress in tumors. In this review, we will describe the cellular processes governed by p97, how the cofactors interact with both p97 and its ubiquitinated substrates, p97 enzymology and the current status in developing p97 inhibitors for cancer therapy.

Design, selection, and development of cyclic peptide ligands for human erythropoietin

2017 ◽  
Vol 1500 ◽  
pp. 105-120 ◽  
Author(s):  
William S. Kish ◽  
Hiroyuki Sachi ◽  
Amith D. Naik ◽  
Matthew K. Roach ◽  
Benjamin G. Bobay ◽  
...  
Keyword(s):  
Cyclic Peptide ◽  
Peptide Ligands ◽  
Human Erythropoietin ◽  
Design Selection

scholarly journals Proteasomes: unfoldase-assisted protein degradation machines

2019 ◽  
Vol 401 (1) ◽  
pp. 183-199 ◽  
Author(s):  
Parijat Majumder ◽  
Wolfgang Baumeister
Keyword(s):  
Stress Response ◽  
Molecular Machines ◽  
Molecular Architecture ◽  
Core Particle ◽  
Protein Substrates ◽  
Macromolecular Assemblies ◽  
Current State ◽  
Intracellular Proteins ◽  
Domains Of Life ◽  
Aaa Atpases

Abstract Proteasomes are the principal molecular machines for the regulated degradation of intracellular proteins. These self-compartmentalized macromolecular assemblies selectively degrade misfolded, mistranslated, damaged or otherwise unwanted proteins, and play a pivotal role in the maintenance of cellular proteostasis, in stress response, and numerous other processes of vital importance. Whereas the molecular architecture of the proteasome core particle (CP) is universally conserved, the unfoldase modules vary in overall structure, subunit complexity, and regulatory principles. Proteasomal unfoldases are AAA+ ATPases (ATPases associated with a variety of cellular activities) that unfold protein substrates, and translocate them into the CP for degradation. In this review, we summarize the current state of knowledge about proteasome – unfoldase systems in bacteria, archaea, and eukaryotes, the three domains of life.

scholarly journals Stoichiometry of Nucleotide Binding to Proteasome AAA+ ATPase Hexamer Established by Native Mass Spectrometry

2020 ◽  
Vol 19 (12) ◽  
pp. 1997-2014
Author(s):  
Yadong Yu ◽  
Haichuan Liu ◽  
Zanlin Yu ◽  
H. Ewa Witkowska ◽  
Yifan Cheng
Keyword(s):  
Protein Unfolding ◽  
Atp Hydrolysis ◽  
Mass Measurement ◽  
Site Occupancy ◽  
Internal Standard ◽  
Large Family ◽  
Nucleotide Binding ◽  
Native Mass Spectrometry ◽  
Aaa Atpase ◽  
Aaa Atpases

AAA+ ATPases constitute a large family of proteins that are involved in a plethora of cellular processes including DNA disassembly, protein degradation and protein complex disassembly. They typically form a hexametric ring-shaped structure with six subunits in a (pseudo) 6-fold symmetry. In a subset of AAA+ ATPases that facilitate protein unfolding and degradation, six subunits cooperate to translocate protein substrates through a central pore in the ring. The number and type of nucleotides in an AAA+ ATPase hexamer is inherently linked to the mechanism that underlies cooperation among subunits and couples ATP hydrolysis with substrate translocation. We conducted a native MS study of a monodispersed form of PAN, an archaeal proteasome AAA+ ATPase, to determine the number of nucleotides bound to each hexamer of the WT protein. We utilized ADP and its analogs (TNP-ADP and mant-ADP), and a nonhydrolyzable ATP analog (AMP-PNP) to study nucleotide site occupancy within the PAN hexamer in ADP- and ATP-binding states, respectively. Throughout all experiments we used a Walker A mutant (PANK217A) that is impaired in nucleotide binding as an internal standard to mitigate the effects of residual solvation on mass measurement accuracy and to serve as a reference protein to control for nonspecific nucleotide binding. This approach led to the unambiguous finding that a WT PAN hexamer carried – from expression host – six tightly bound ADP molecules that could be exchanged for ADP and ATP analogs. Although the Walker A mutant did not bind ADP analogs, it did bind AMP-PNP, albeit at multiple stoichiometries. We observed variable levels of hexamer dissociation and an appearance of multimeric species with the over-charged molecular ion distributions across repeated experiments. We posit that these phenomena originated during ESI process at the final stages of ESI droplet evolution.

scholarly journals A Retrospective on eIF2A—and Not the Alpha Subunit of eIF2

2020 ◽  
Vol 21 (6) ◽  
pp. 2054
Author(s):  
Anton A. Komar ◽  
William C. Merrick
Keyword(s):  
Translational Control ◽  
Ribosomal Subunit ◽  
Initiation Factor ◽  
Single Chain ◽  
Initiation Factors ◽  
Eif2α Phosphorylation ◽  
Specific Mrnas ◽  
Internal Initiation ◽  
And Function ◽  
Polypeptide Chains

Initiation of protein synthesis in eukaryotes is a complex process requiring more than 12 different initiation factors, comprising over 30 polypeptide chains. The functions of many of these factors have been established in great detail; however, the precise role of some of them and their mechanism of action is still not well understood. Eukaryotic initiation factor 2A (eIF2A) is a single chain 65 kDa protein that was initially believed to serve as the functional homologue of prokaryotic IF2, since eIF2A and IF2 catalyze biochemically similar reactions, i.e., they stimulate initiator Met-tRNAi binding to the small ribosomal subunit. However, subsequent identification of a heterotrimeric 126 kDa factor, eIF2 (α,β,γ) showed that this factor, and not eIF2A, was primarily responsible for the binding of Met-tRNAi to 40S subunit in eukaryotes. It was found however, that eIF2A can promote recruitment of Met-tRNAi to 40S/mRNA complexes under conditions of inhibition of eIF2 activity (eIF2α-phosphorylation), or its absence. eIF2A does not function in major steps in the initiation process, but is suggested to act at some minor/alternative initiation events such as re-initiation, internal initiation, or non-AUG initiation, important for translational control of specific mRNAs. This review summarizes our current understanding of the eIF2A structure and function.

scholarly journals Inter-ring rotations of AAA ATPase p97 revealed by electron cryomicroscopy

Open Biology ◽  
2014 ◽  
Vol 4 (3) ◽  
pp. 130142 ◽  
Author(s):  
Heidi O. Yeung ◽  
Andreas Förster ◽  
Cecilia Bebeacua ◽  
Hajime Niwa ◽  
Caroline Ewens ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Protein Complexes ◽  
Cell Cycle Control ◽  
Conformational Heterogeneity ◽  
Electron Cryomicroscopy ◽  
Aaa Atpase ◽  
Protein Substrates ◽  
Ubiquitin System ◽  
Aaa Protein ◽  
Ubiquitylated Protein

The type II AAA+ protein p97 is involved in numerous cellular activities, including endoplasmic reticulum-associated degradation, transcription activation, membrane fusion and cell-cycle control. These activities are at least in part regulated by the ubiquitin system, in which p97 is thought to target ubiquitylated protein substrates within macromolecular complexes and assist in their extraction or disassembly. Although ATPase activity is essential for p97 function, little is known about how ATP binding or hydrolysis is coupled with p97 conformational changes and substrate remodelling. Here, we have used single-particle electron cryomicroscopy (cryo-EM) to study the effect of nucleotides on p97 conformation. We have identified conformational heterogeneity within the cryo-EM datasets from which we have resolved two major p97 conformations. A comparison of conformations reveals inter-ring rotations upon nucleotide binding and hydrolysis that may be linked to the remodelling of target protein complexes.

scholarly journals Structure of the Cdc48 segregase in the act of unfolding an authentic substrate

Science ◽  
2019 ◽  
Vol 365 (6452) ◽  
pp. 502-505 ◽  
Author(s):  
Ian Cooney ◽  
Han Han ◽  
Michael G. Stewart ◽  
Richard H. Carson ◽  
Daniel T. Hansen ◽  
...  
Keyword(s):  
Protein Translocation ◽  
Substrate Binding ◽  
Adaptor Protein ◽  
Biological Pathways ◽  
Protein Substrates ◽  
Adenosine Triphosphatases ◽  
Binding Residues ◽  
Aaa Atpases ◽  
Helical Configuration ◽  
Resolution Structure

The cellular machine Cdc48 functions in multiple biological pathways by segregating its protein substrates from a variety of stable environments such as organelles or multi-subunit complexes. Despite extensive studies, the mechanism of Cdc48 has remained obscure, and its reported structures are inconsistent with models of substrate translocation proposed for other AAA+ ATPases (adenosine triphosphatases). Here, we report a 3.7-angstrom–resolution structure of Cdc48 in complex with an adaptor protein and a native substrate. Cdc48 engages substrate by adopting a helical configuration of substrate-binding residues that extends through the central pore of both of the ATPase rings. These findings indicate a unified hand-over-hand mechanism of protein translocation by Cdc48 and other AAA+ ATPases.

scholarly journals Cytoplasmic dynein regulates its attachment to microtubules via nucleotide state-switched mechanosensing at multiple AAA domains

2015 ◽  
Vol 112 (20) ◽  
pp. 6371-6376 ◽  
Author(s):  
Matthew P. Nicholas ◽  
Florian Berger ◽  
Lu Rao ◽  
Sibylle Brenner ◽  
Carol Cho ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Atp Hydrolysis ◽  
Cytoplasmic Dynein ◽  
Atp Binding ◽  
Mechanical Tension ◽  
Main Site ◽  
Aaa Atpase ◽  
C Terminus ◽  
Directed Motility ◽  
Aaa Atpases

Cytoplasmic dynein is a homodimeric microtubule (MT) motor protein responsible for most MT minus-end–directed motility. Dynein contains four AAA+ ATPases (AAA: ATPase associated with various cellular activities) per motor domain (AAA1–4). The main site of ATP hydrolysis, AAA1, is the only site considered by most dynein motility models. However, it remains unclear how ATPase activity and MT binding are coordinated within and between dynein’s motor domains. Using optical tweezers, we characterize the MT-binding strength of recombinant dynein monomers as a function of mechanical tension and nucleotide state. Dynein responds anisotropically to tension, binding tighter to MTs when pulled toward the MT plus end. We provide evidence that this behavior results from an asymmetrical bond that acts as a slip bond under forward tension and a slip-ideal bond under backward tension. ATP weakens MT binding and reduces bond strength anisotropy, and unexpectedly, so does ADP. Using nucleotide binding and hydrolysis mutants, we show that, although ATP exerts its effects via binding AAA1, ADP effects are mediated by AAA3. Finally, we demonstrate “gating” of AAA1 function by AAA3. When tension is absent or applied via dynein’s C terminus, ATP binding to AAA1 induces MT release only if AAA3 is in the posthydrolysis state. However, when tension is applied to the linker, ATP binding to AAA3 is sufficient to “open” the gate. These results elucidate the mechanisms of dynein–MT interactions, identify regulatory roles for AAA3, and help define the interplay between mechanical tension and nucleotide state in regulating dynein motility.

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