Probing Tubulin-Blocked State of VDAC by Varying Membrane Surface Charge
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Other documents of the author: Gurnev, Philip A.; Queralt-Martín, María; Aguilella, Vicente; Rostovtseva, Tatiana K.
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Show full item recordcomunitat-uji-handle:10234/9
comunitat-uji-handle2:10234/2507
comunitat-uji-handle3:10234/6973
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Title
Probing Tubulin-Blocked State of VDAC by Varying Membrane Surface ChargeDate
2012-05Publisher
Biophysical SocietyType
info:eu-repo/semantics/articleVersion
info:eu-repo/semantics/publishedVersionSubject
vdac | charge | tubulin | state | channel selectivity inversion | lipid | surface charge | conductance | membrane surface | membrane | probe | mitochondrial | salt concentration | salt | blockage
Description
Reversible blockage of the voltage-dependent anion channel (VDAC) of the mitochondrial outer membrane by dimeric tubulin is being recognized as a potent regulator of mitochondrial respiration. The tubulin-blocked state ... [+]
Reversible blockage of the voltage-dependent anion channel (VDAC) of the mitochondrial outer membrane by dimeric tubulin is being recognized as a potent regulator of mitochondrial respiration. The tubulin-blocked state of VDAC is impermeant for ATP but only partially closed for small ions. This residual conductance allows studying the nature of the tubulin-blocked state in single-channel reconstitution experiments. Here we probe this state by changing lipid bilayer charge from positive to neutral to negative. We find that voltage sensitivity of the tubulin-VDAC blockage practically does not depend on the lipid charge and salt concentration with the effective gating charge staying within the range of 10–14 elementary charges. At physiologically relevant low salt concentrations, the conductance of the tubulin-blocked state is decreased by positive and increased by negative charge of the lipids, whereas the conductance of the open channel is much less sensitive to this param- eter. Such a behavior supports the model in which tubulin’s negatively charged tail enters the VDAC pore, inverting its anionic selectivity to cationic and increasing proximity of ion pathways to the nearest lipid charges as compared with the open state of the channel. [-]
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Byophysical Journal, v. 102, issue 9 (May 2012)Rights
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info:eu-repo/semantics/openAccess
info:eu-repo/semantics/openAccess
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