scholarly journals Mechanism of CFTR correction by type I folding correctors

2021 ◽  
Author(s):  
Jue Chen ◽  
Karol Fiedorczuk
Keyword(s):  
Electron Microscopy ◽  
Cystic Fibrosis ◽  
Mechanism Of Action ◽  
Protein Misfolding ◽  
Transmembrane Domain ◽  
Early Stage ◽  
Type I ◽  
Hydrophobic Pocket ◽  
Cryo Electron Microscopy ◽  
Δf508 Cftr

Small molecule chaperones have been exploited as therapeutics for the hundreds of diseases caused by protein misfolding. The most successful examples are the CFTR correctors, which transformed cystic fibrosis therapy. These molecules revert folding defects of the ΔF508 mutant and are widely used to treat patients. However, their mechanism of action is unknown. Here we present cryo-electron microscopy structures of CFTR in complex with two FDA-approved correctors: lumacaftor and tezacaftor. Both drugs insert into a hydrophobic pocket in the first transmembrane domain (TMD1), linking together four helices that are thermodynamically unstable. Mutating residues at the binding site rendered ΔF508-CFTR insensitive to lumacaftor and tezacaftor, underscoring the functional significance of the structural discovery. These results support a mechanism in which the correctors stabilize TMD1 at an early stage of biogenesis, prevent its pre-mature degradation, and thereby allosterically rescue a large number of disease-causing mutations.

scholarly journals Structure of the Infective Getah Virus at 2.8 Å-resolution Determined by Cryo-electron Microscopy

2021 ◽  
Author(s):  
Aojie Wang ◽  
Feng Zhou ◽  
Congcong Liu ◽  
Dongsheng Gao ◽  
Ruxi Qi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Immune Evasion ◽  
Cell Invasion ◽  
Structural Information ◽  
Host Cell Invasion ◽  
Hydrophobic Pocket ◽  
Viral Immune Evasion ◽  
Cryo Electron Microscopy ◽  
Reproductive Losses ◽  
Getah Virus

Getah virus (GETV) is a mosquito-borne pathogen that can cause a mild illness and reproductive losses in animals. Although antibodies to GETV have been found in humans, there are no reports of clinical symptom associated with GETV. However, antivirals or vaccine against GETV is still unavailable due to lack of knowledge of the structure of GETV virion. Here, we present the structure of mature GETV at a resolution of 2.8 Å with capsid protein, envelope glycoproteins E1 and E2. Glycosylation and S-acylation sites in E1 and E2 are identified. The surface-exposed glycans demonstrated their impact on the viral immune evasion and host cell invasion. The S-acylation sites strongly stabilize the virion. In addition, a cholesterol and phospholipid molecule are observed in transmembrane hydrophobic pocket, together with two more cholesterols surround the pocket. These structural information are helpful for structure-based antivirals and vaccine design.

scholarly journals Structure of the human epithelial sodium channel by cryo-electron microscopy

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Sigrid Noreng ◽  
Arpita Bharadwaj ◽  
Richard Posert ◽  
Craig Yoshioka ◽  
Isabelle Baconguis
Keyword(s):  
Electron Microscopy ◽  
Ion Channel ◽  
Sodium Channel ◽  
Conformational Changes ◽  
Single Particle ◽  
Transmembrane Domain ◽  
Epithelial Sodium Channel ◽  
Cryo Electron Microscopy ◽  
Inhibitory Domain ◽  
Epithelial Sodium Channel Enac

The epithelial sodium channel (ENaC), a member of the ENaC/DEG superfamily, regulates Na+ and water homeostasis. ENaCs assemble as heterotrimeric channels that harbor protease-sensitive domains critical for gating the channel. Here, we present the structure of human ENaC in the uncleaved state determined by single-particle cryo-electron microscopy. The ion channel is composed of a large extracellular domain and a narrow transmembrane domain. The structure reveals that ENaC assembles with a 1:1:1 stoichiometry of α:β:γ subunits arranged in a counter-clockwise manner. The shape of each subunit is reminiscent of a hand with key gating domains of a ‘finger’ and a ‘thumb.’ Wedged between these domains is the elusive protease-sensitive inhibitory domain poised to regulate conformational changes of the ‘finger’ and ‘thumb’; thus, the structure provides the first view of the architecture of inhibition of ENaC.

scholarly journals Understanding IGF-II Action through Insights into Receptor Binding and Activation

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2276 ◽  
Author(s):  
Andrew J. Blyth ◽  
Nicholas S. Kirk ◽  
Briony E. Forbes
Keyword(s):  
Electron Microscopy ◽  
Growth Factor ◽  
Mechanism Of Action ◽  
Growth And Development ◽  
Growth And Survival ◽  
Igf System ◽  
Cryo Electron Microscopy ◽  
Igf I ◽  
Recent Developments ◽  
Cancer Types

The insulin-like growth factor (IGF) system regulates metabolic and mitogenic signaling through an intricate network of related receptors and hormones. IGF-II is one of several hormones within this system that primarily regulates mitogenic functions and is especially important during fetal growth and development. IGF-II is also found to be overexpressed in several cancer types, promoting growth and survival. It is also unique in the IGF system as it acts through both IGF-1R and insulin receptor isoform A (IR-A). Despite this, IGF-II is the least investigated ligand of the IGF system. This review will explore recent developments in IGF-II research including a structure of IGF-II bound to IGF-1R determined using cryo-electron microscopy (cryoEM). Comparisons are made with the structures of insulin and IGF-I bound to their cognate receptors. Finally discussed are outstanding questions in the mechanism of action of IGF-II with the goal of developing antagonists of IGF action in cancer.

scholarly journals Structural basis of prokaryotic ubiquitin-like protein engagement and translocation by the mycobacterial Mpa-proteasome complex

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Mikhail Kavalchuk ◽  
Ahmad Jomaa ◽  
Andreas U. Müller ◽  
Eilika Weber-Ban
Keyword(s):  
Electron Microscopy ◽  
Mycobacterium Tuberculosis ◽  
Early Stage ◽  
Structural Basis ◽  
Human Pathogen ◽  
Core Particle ◽  
Cryo Electron Microscopy ◽  
Complementary Interactions

AbstractProteasomes are present in eukaryotes, archaea and Actinobacteria, including the human pathogen Mycobacterium tuberculosis, where proteasomal degradation supports persistence inside the host. In mycobacteria and other members of Actinobacteria, prokaryotic ubiquitin-like protein (Pup) serves as a degradation tag post-translationally conjugated to target proteins for their recruitment to the mycobacterial proteasome ATPase (Mpa). Here, we use single-particle cryo-electron microscopy to determine the structure of Mpa in complex with the 20S core particle at an early stage of pupylated substrate recruitment, shedding light on the mechanism of substrate translocation. Two conformational states of Mpa show how substrate is translocated stepwise towards the degradation chamber of the proteasome core particle. We also demonstrate, in vitro and in vivo, the importance of a structural feature in Mpa that allows formation of alternating charge-complementary interactions with the proteasome resulting in radial, rail-guided movements during the ATPase conformational cycle.

scholarly journals A posttranslational modification code for CFTR maturation is altered in cystic fibrosis

2019 ◽  
Vol 12 (562) ◽  
pp. eaan7984 ◽  
Author(s):  
Sandra Pankow ◽  
Casimir Bamberger ◽  
John R. Yates
Keyword(s):  
Cystic Fibrosis ◽  
Posttranslational Modifications ◽  
Protein Misfolding ◽  
Secretory Pathway ◽  
Point Mutations ◽  
Wild Type ◽  
Er Quality Control ◽  
Multiple Organs ◽  
Δf508 Cftr ◽  
And Function

The multistep process regulating the maturation of membrane proteins in the endoplasmic reticulum (ER) and the secretory pathway is disrupted in many protein misfolding disorders. Mutations in the ion channel CFTR that impair its folding and subsequent localization to the plasma membrane cause cystic fibrosis (CF), an inherited and eventually lethal disease that impairs the function of multiple organs, mostly the lungs. Here, we found that proper maturation of CFTR is dependent on cross-talk between phosphorylation and methylation events in the regulatory insertion (RI) element of the protein. Manipulating these posttranslational modifications (PTMs) prevented the maturation of wild-type CFTR and instead induced its degradation by ER quality control systems. Deletion of Phe508(ΔF508), the most prevalent mutation in CF, and other mutations in CFTR that impair its trafficking, such as N1303K, also led to quantitative and qualitative PTM changes that prevented the maturation of misfolded CFTR. Further analysis revealed that a wild-type CFTR–like PTM pattern and function was restored in ΔF508 CFTR when cells were cultured at 28°C but only in the presence of the kinase CK2α. Furthermore, the ability to replicate this PTM pattern predicted the efficacy of treatments in restoring ΔF508 CFTR activity. Accordingly, evaluation of patient information revealed that point mutations of several of the modification sites are associated with clinical CF. These findings identify a minimal quantitative and qualitative PTM code for CFTR maturation that distinguishes correctly folded from misfolded CFTR.

scholarly journals ATP and Substrate Binding Regulates Conformational Changes of Human Peroxisomal ABC Transporter ALDP

2021 ◽  
Author(s):  
Lin Tang ◽  
Chao Xiong ◽  
Lina Jia ◽  
Ming-He Shen ◽  
Wei-Xi Xiong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fatty Acids ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Long Chain Fatty Acids ◽  
Variable Size ◽  
Binding Domains ◽  
Cryo Electron Microscopy ◽  
Peroxisome Membrane ◽  
Long Chain

Abstract The malfunction of ABCD1 causes X-linked adrenoleukodystrophy (X-ALD), a rare neurodegenerative disease that affect all tissues in human. Residing in the peroxisome membrane, ABCD1 plays a role in the translocation of very long chain fatty acids (VLCFA) for their damage by β-oxidation. Here, we present five Cryo-Electron microscopy structures of ABCD1 in four conformational states. Combined with functional analysis, we found that substrate and ATP trigger the closing of two nucleotide binding domains (NBDs) over a distance of 40 Å and the rearrangement of the transmembrane domains. Each of the three inward-facing structure of ABCD1 has a vestibule opens to cytosol with variable size. Furthermore, the structure of ABCD1 in the outward-facing state supports that ATP molecules pull the two NBDs together and open the transmembrane domain to the peroxisomal lumen for substrate release. The five structures provide a snapshot of substrate transporting cycle and mechanistic implications for disease-causing mutations.

scholarly journals Five of Five VHHs Neutralizing Poliovirus Bind the Receptor-Binding Site

2016 ◽  
Vol 90 (7) ◽  
pp. 3496-3505 ◽  
Author(s):  
Mike Strauss ◽  
Lise Schotte ◽  
Bert Thys ◽  
David J. Filman ◽  
James M. Hogle
Keyword(s):  
Electron Microscopy ◽  
Quality Control ◽  
Binding Site ◽  
Receptor Binding ◽  
Viral Entry ◽  
Early Stage ◽  
Antiviral Agents ◽  
Receptor Binding Site ◽  
Cryo Electron Microscopy

ABSTRACTNanobodies, or VHHs, that recognize poliovirus type 1 have previously been selected and characterized as candidates for antiviral agents or reagents for standardization of vaccine quality control. In this study, we present high-resolution cryo-electron microscopy reconstructions of poliovirus with five neutralizing VHHs. All VHHs bind the capsid in the canyon at sites that extensively overlap the poliovirus receptor-binding site. In contrast, the interaction involves a unique (and surprisingly extensive) surface for each of the five VHHs. Five regions of the capsid were found to participate in binding with all five VHHs. Four of these five regions are known to alter during the expansion of the capsid associated with viral entry. Interestingly, binding of one of the VHHs, PVSS21E, resulted in significant changes of the capsid structure and thus seems to trap the virus in an early stage of expansion.IMPORTANCEWe describe the cryo-electron microscopy structures of complexes of five neutralizing VHHs with the Mahoney strain of type 1 poliovirus at resolutions ranging from 3.8 to 6.3Å. All five VHHs bind deep in the virus canyon at similar sites that overlap extensively with the binding site for the receptor (CD155). The binding surfaces on the VHHs are surprisingly extensive, but despite the use of similar binding surfaces on the virus, the binding surface on the VHHs is unique for each VHH. In four of the five complexes, the virus remains essentially unchanged, but for the fifth there are significant changes reminiscent of but smaller in magnitude than the changes associated with cell entry, suggesting that this VHH traps the virus in a previously undescribed early intermediate state. The neutralizing mechanisms of the VHHs and their potential use as quality control agents for the end game of poliovirus eradication are discussed.

scholarly journals Cryo-EM structures of calcium homeostasis modulator channels in diverse oligomeric assemblies

2020 ◽  
Vol 6 (29) ◽  
pp. eaba8105 ◽  
Author(s):  
Kanae Demura ◽  
Tsukasa Kusakizako ◽  
Wataru Shihoya ◽  
Masahiro Hiraizumi ◽  
Kengo Nomura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Caenorhabditis Elegans ◽  
Adenosine Triphosphate ◽  
Calcium Homeostasis ◽  
Transmembrane Domain ◽  
Atp Release ◽  
Channel Pore ◽  
Cryo Electron Microscopy ◽  
Chimeric Construct ◽  
Intersubunit Interactions

Calcium homeostasis modulator (CALHM) family proteins are Ca2+-regulated adenosine triphosphate (ATP)–release channels involved in neural functions including neurotransmission in gustation. Here, we present the cryo–electron microscopy (EM) structures of killifish CALHM1, human CALHM2, and Caenorhabditis elegans CLHM-1 at resolutions of 2.66, 3.4, and 3.6 Å, respectively. The CALHM1 octamer structure reveals that the N-terminal helix forms the constriction site at the channel pore in the open state and modulates the ATP conductance. The CALHM2 undecamer and CLHM-1 nonamer structures show the different oligomeric stoichiometries among CALHM homologs. We further report the cryo-EM structures of the chimeric construct, revealing that the intersubunit interactions at the transmembrane domain (TMD) and the TMD–intracellular domain linker define the oligomeric stoichiometry. These findings advance our understanding of the ATP conduction and oligomerization mechanisms of CALHM channels.

scholarly journals Cryo-EM structures and transport mechanism of human P5B type ATPase ATP13A2

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xudong Chen ◽  
Mingze Zhou ◽  
Sensen Zhang ◽  
Jian Yin ◽  
Ping Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neurodegenerative Disorders ◽  
Mammalian Cells ◽  
Transport Mechanism ◽  
Transmembrane Domain ◽  
Normal Function ◽  
Cryo Electron Microscopy ◽  
Polyamine Transport ◽  
Adenosine Triphosphatases ◽  
Transport Cycle

AbstractPolyamines are important polycations that play critical roles in mammalian cells. ATP13A2 belongs to the orphan P5B adenosine triphosphatases (ATPase) family and has been established as a lysosomal polyamine exporter to maintain the normal function of lysosomes and mitochondria. Previous studies have reported that several human neurodegenerative disorders are related to mutations in the ATP13A2 gene. However, the transport mechanism of ATP13A2 in the lysosome remains unclear. Here, we report the cryo-electron microscopy (cryo-EM) structures of three distinct intermediates of the human ATP13A2, revealing key insights into the spermine (SPM) transport cycle in the lysosome. The transmembrane domain serves as a substrate binding site and the C-terminal domain is essential for protein stability and may play a regulatory role. These findings advance our understanding of the polyamine transport mechanism, the lipid-associated regulation, and the disease-associated mutants of ATP13A2.

scholarly journals Comprehensive mapping of Cystic Fibrosis mutations to CFTR protein identifies mutation clusters and molecular docking predicts corrector binding site

2018 ◽  
Author(s):  
Steven V. Molinski ◽  
Vijay M. Shahani ◽  
Adithya S. Subramanian ◽  
Stephen S. MacKinnon ◽  
Geoffrey Woollard ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cystic Fibrosis ◽  
Molecular Docking ◽  
Binding Site ◽  
Tertiary Structure ◽  
Class I ◽  
Channel State ◽  
Cryo Electron Microscopy ◽  
Cftr Protein

AbstractBackgroundCystic Fibrosis (CF) is caused by mutations in the CFTR gene, of which over 2000 have been reported to date. Mutations have yet to be analyzed in aggregate to assess their distribution across the tertiary structure of the CFTR protein, an approach that could provide valuable insights into the structure-function relationship of CFTR. In addition, the binding site of Class I correctors (VX-809, VX-661, C18) is not well understood.MethodsExonic CFTR mutations and mutant allele frequencies described in three curated databases (ABCMdb, CFTR1 and CFTR2, comprising >130,000 data points) were mapped to two different structural models: a homology model of full-length CFTR protein in the open-channel state, and a cryo-electron microscopy core-structure of CFTR in the closed-channel state. Immunoblotting confirmed the approximate binding site of Class I correctors, and molecular docking generated binding poses for their complex with the cryo-electron microscopy structure.ResultsResidue positions of six high-frequency mutant CFTR alleles were found to spatially co-localize in CFTR protein, and a significant cluster was identified at the NBD1:ICL4 interdomain interface. Further, Class I correctors VX-809, VX-661 and C18 were shown to act via a similar mechanism in vitro, and a putative multi-domain corrector binding site near residues F374-L375 was predicted in silico.ConclusionsOur results confirm the significance of interdomain interfaces as susceptible to disruptive mutation, and identify a putative corrector binding site. The structural pharmacogenomics approach of mapping mutation databases to protein models shows promise for facilitating drug discovery and personalized medicine for monogenetic diseases.

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