Philip A. Gurnev

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Highly reproducible ion channels of the lipopeptide antibiotic syringomycin E demonstrate unprecedented involvement of the host bilayer lipids. We find that in addition to a pronounced influence of lipid species on the open-channel ionic conductance, the membrane lipids play a crucial role in channel gating. The effective gating charge, which characterizes(More)
Elucidating molecular mechanisms by which lipids regulate protein function within biological membranes is critical for understanding the many cellular processes. Recently, we have found that dimeric αβ-tubulin, a subunit of microtubules, regulates mitochondrial respiration by blocking the voltage-dependent anion channel (VDAC) of mitochondrial outer(More)
We studied membrane activity of the bacterial peptide TisB involved in persister cell formation. TisB and its analogs form multi-state ion-conductive pores in planar lipid bilayers with all states displaying similar anionic selectivity. TisB analogs differing by ±1 elementary charges show corresponding changes in selectivity. Probing TisB pores with(More)
The effect of syringotoxin (ST), a member of the cyclic lipodepsipeptides family (CLPs) produced by Pseudomonas syringae pv. syringae on the membrane permeability of human red blood cells (RBCs) and model bilayer lipid membranes (BLMs) was studied and compared to that of two recently investigated CLPs, syringomycin E (SRE) and syringopeptin 22A (SP22A)(More)
Recently reported functional interaction between voltage-dependent anion channel of the outer mitochondrial membrane, VDAC, and dimeric tubulin is observed as a reversible channel blockage. Using partitioning of poly-(ethylene glycol)s of different molecular weights and reversal potential measurements, we probe the size and ion selectivity of the fully open(More)
To probe the size of the ion channel formed by Pseudomonas syringae lipodepsipeptide syringomycin E, we use the partial blockage of ion current by penetrating poly(ethylene glycol)s. Earlier experiments with symmetric application of these polymers yielded a radius estimate of approximately 1 nm. Now, motivated by the asymmetric non-ohmic current-voltage(More)
Gauging the interactions of a natively unfolded Parkinson disease-related protein, alpha-synuclein (α-syn) with membranes and its pathways between and within cells is important for understanding its pathogenesis. Here, to address these questions, we use a robust β-barrel channel, α-hemolysin, reconstituted into planar lipid bilayers. Transient, ~95%(More)
We demonstrate that the cation-selective channel formed by gramicidin A can be used as a reliable sensor for studying the multivalent ion accumulation at the surfaces of charged lipid membranes and the "charge inversion" phenomenon. In asymmetrically charged membranes with the individual leaflets formed from pure negative and positive lipids bathed by 0.1 M(More)
To elucidate the voltage gating of syringomycin E (SRE) ion channels in lipid bilayers, the effective gating charge q was measured under different conditions. It was shown that q and its sign are dependent on membrane surface charge, dipole potential, and the outer potential (Delta phi). The q values were positive for charged bilayers and negative for(More)
Participation of the small, intrinsically disordered protein α-synuclein (α-syn) in Parkinson disease (PD) pathogenesis has been well documented. Although recent research demonstrates the involvement of α-syn in mitochondrial dysfunction in neurodegeneration and suggests direct interaction of α-syn with mitochondria, the molecular mechanism(s) of α-syn(More)