scholarly journals High Resolution Structure and Double Electron-Electron Resonance of the Zebrafish Voltage-dependent Anion Channel 2 Reveal an Oligomeric Population

2014 ◽  
Vol 289 (18) ◽  
pp. 12566-12577 ◽  
Author(s):  
Johann Schredelseker ◽  
Aviv Paz ◽  
Carlos J. López ◽  
Christian Altenbach ◽  
Calvin S. Leung ◽  
...  
Keyword(s):  
High Resolution ◽  
Anion Channel ◽  
Voltage Dependent Anion Channel ◽  
Electron Resonance ◽  
Double Electron ◽  
Voltage Dependent ◽  
High Resolution Structure ◽  
Double Electron Electron Resonance ◽  
Resolution Structure

scholarly journals Protonation state of glutamate 73 regulates the formation of a specific dimeric association of mVDAC1

2017 ◽  
Vol 115 (2) ◽  
pp. E172-E179 ◽  
Author(s):  
Lucie A. Bergdoll ◽  
Michael T. Lerch ◽  
John W. Patrick ◽  
Kendrick Belardo ◽  
Christian Altenbach ◽  
...  
Keyword(s):  
Metabolic Regulation ◽  
Anion Channel ◽  
Native Mass Spectrometry ◽  
Low Ph ◽  
Affinity Constant ◽  
Voltage Dependent Anion Channel ◽  
Oligomeric State ◽  
Voltage Dependent ◽  
Double Electron Electron Resonance ◽  
Intermolecular Distances

The voltage-dependent anion channel (VDAC) is the most abundant protein in the outer mitochondrial membrane and constitutes the primary pathway for the exchange of ions and metabolites between the cytosol and the mitochondria. There is accumulating evidence supporting VDAC’s role in mitochondrial metabolic regulation and apoptosis, where VDAC oligomerization has been implicated with these processes. Herein, we report a specific pH-dependent dimerization of murine VDAC1 (mVDAC1) identified by double electron–electron resonance and native mass spectrometry. Intermolecular distances on four singly spin-labeled mVDAC1 mutants were used to generate a model of the low-pH dimer, establishing the presence of residue E73 at the interface. This dimer arrangement is different from any oligomeric state previously described, and it forms as a steep function of pH with an apparent pKa of 7.4. Moreover, the monomer–dimer equilibrium affinity constant was determined using native MS, revealing a nearly eightfold enhancement in dimerization affinity at low pH. Mutation of E73 to either alanine or glutamine severely reduces oligomerization, demonstrating the role of protonated E73 in enhancing dimer formation. Based on these results, and the known importance of E73 in VDAC physiology, VDAC dimerization likely plays a significant role in mitochondrial metabolic regulation and apoptosis in response to cytosolic acidification during cellular stress.

scholarly journals MicroED structure of lipid-embedded mammalian mitochondrial voltage dependent anion channel

2020 ◽  
Author(s):  
Michael W. Martynowycz ◽  
Farha Khan ◽  
Johan Hattne ◽  
Jeff Abramson ◽  
Tamir Gonen
Keyword(s):  
Membrane Protein ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Anion Channel ◽  
Voltage Dependent Anion Channel ◽  
X Ray Crystallography ◽  
Voltage Dependent ◽  
Crystal Contacts ◽  
Viscous Media ◽  
Resolution Structure

AbstractA near-atomic resolution structure of the mouse voltage dependent anion channel (mVDAC) is determined by combining cryogenic focused ion-beam (FIB) milling and microcrystal electron diffraction (MicroED). The crystals were grown in a viscous modified bicelle suspension which limited their size and made them unsuitable for conventional X-ray crystallography. Individual thin, plate-like crystals were identified using scanning electron microscopy (SEM) and focused ion-beam (FIB) imaging at high magnification. Three crystals were milled into thin lamellae. MicroED data were collected from each lamellae and merged to increase completeness. Unmodelled densities were observed between protein monomers, suggesting the presence of lipids that likely mediate crystal contacts. This work demonstrates the utility of milling membrane protein microcrystals grown in viscous media using a focused ion-beam for subsequent structure determination by MicroED for samples that are not otherwise tractable by other crystallographic methods. To our knowledge, the structure presented here is the first of a membrane protein crystallized in a lipid matrix and solved by MicroED.

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance

2019 ◽  
Author(s):  
Dennis Bücker ◽  
Annika Sickinger ◽  
Julian D. Ruiz Perez ◽  
Manuel Oestringer ◽  
Stefan Mecking ◽  
...  
Keyword(s):  
Chain Length ◽  
Length Distribution ◽  
Catalyst System ◽  
Chain Conformation ◽  
Controlled Polymerization ◽  
Chain Length Distribution ◽  
Electron Resonance ◽  
Double Electron ◽  
The Individual ◽  
Double Electron Electron Resonance

Synthetic polymers are mixtures of different length chains, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.

In-Cell Double Electron–Electron Resonance at Nanomolar Protein Concentrations

2021 ◽  
pp. 3679-3684
Author(s):  
Svetlana Kucher ◽  
Christina Elsner ◽  
Mariya Safonova ◽  
Stefano Maffini ◽  
Enrica Bordignon
Keyword(s):  
Electron Resonance ◽  
Double Electron ◽  
Double Electron Electron Resonance

scholarly journals VDAC1 in the diseased myocardium and the effect of VDAC1-interacting compound on atrial fibrosis induced by hyperaldosteronism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hadar Klapper-Goldstein ◽  
Ankit Verma ◽  
Sigal Elyagon ◽  
Roni Gillis ◽  
Michael Murninkas ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Apoptotic Cell ◽  
Anion Channel ◽  
Immunohistochemical Analysis ◽  
Voltage Dependent Anion Channel ◽  
Cardiac Tissues ◽  
Therapeutic Implications ◽  
Voltage Dependent ◽  
Models Of Lupus

AbstractThe voltage-dependent anion channel 1 (VDAC1) is a key player in mitochondrial function. VDAC1 serves as a gatekeeper mediating the fluxes of ions, nucleotides, and other metabolites across the outer mitochondrial membrane, as well as the release of apoptogenic proteins initiating apoptotic cell death. VBIT-4, a VDAC1 oligomerization inhibitor, was recently shown to prevent mitochondrial dysfunction and apoptosis, as validated in mouse models of lupus and type-2 diabetes. In the present study, we explored the expression of VDAC1 in the diseased myocardium of humans and rats. In addition, we evaluated the effect of VBIT-4 treatment on the atrial structural and electrical remodeling of rats exposed to excessive aldosterone levels. Immunohistochemical analysis of commercially available human cardiac tissues revealed marked overexpression of VDAC1 in post-myocardial infarction patients, as well as in patients with chronic ventricular dilatation\dysfunction. In agreement, rats exposed to myocardial infarction or to excessive aldosterone had a marked increase of VDAC1 in both ventricular and atrial tissues. Immunofluorescence staining indicated a punctuated appearance typical for mitochondrial-localized VDAC1. Finally, VBIT-4 treatment attenuated the atrial fibrotic load of rats exposed to excessive aldosterone without a notable effect on the susceptibility to atrial fibrillation episodes induced by burst pacing. Our results indicate that VDAC1 overexpression is associated with myocardial abnormalities in common pathological settings. Our data also indicate that inhibition of the VDAC1 can reduce excessive fibrosis in the atrial myocardium, a finding which may have important therapeutic implications. The exact mechanism\s of this beneficial effect need further studies.

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