Photoswitching of model ion channels in lipid bilayers

Pfeffermann, Juergen; Eicher, Barbara; Boytsov, Danila; Hannesschlaeger, Christof; Galimzyanov, Timur R.; Glasnov, Toma N.; Pabst, Georg; Akimov, Sergey A.; Pohl, Peter

doi:10.1016/j.jphotobiol.2021.112320

Cited by 23 publications

(23 citation statements)

References 55 publications

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“…Illumination at a wavelength of 474 nm switched the conformation of PhoDAG’s photo-sensitive acyl chain from the cis -state into the trans -state, i.e., the cone-shaped PhoDAG-1 transformed into an almost cylindrical lipid, thereby decreasing the absolute value of J 0 [ 27 , 28 ] ( Figure 2 ).…”

Section: Resultsmentioning

confidence: 99%

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Determinants of Lipid Domain Size

Saitov

Kalutsky

Galimzyanov

et al. 2022

IJMS

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Lipid domains less than 200 nm in size may form a scaffold, enabling the concerted function of plasma membrane proteins. The size-regulating mechanism is under debate. We tested the hypotheses that large values of spontaneous monolayer curvature are incompatible with micrometer-sized domains. Here, we used the transition of photoswitchable lipids from their cylindrical conformation to a conical conformation to increase the negative curvature of a bilayer-forming lipid mixture. In contrast to the hypothesis, pre-existing micrometer-sized domains did not dissipate in our planar bilayers, as indicated by fluorescence images and domain mobility measurements. Elasticity theory supports the observation by predicting the zero free energy gain for splitting large domains into smaller ones. It also indicates an alternative size-determining mechanism: The cone-shaped photolipids reduce the line tension associated with lipid deformations at the phase boundary and thus slow down the kinetics of domain fusion. The competing influence of two approaching domains on the deformation of the intervening lipids is responsible for the kinetic fusion trap. Our experiments indicate that the resulting local energy barrier may restrict the domain size in a dynamic system.

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Section: Resultsmentioning

confidence: 99%

“…Atto565-DPPE and Atto633-PPE were excited at 561 nm and 633 nm, respectively. We used a Polychrome V monochromator (TILL Photonics, Gräfelfing, Germany) to switch PhDAG-1 from its trans to its cis state by illumination at 365 nm and back by illumination at 475 nm light [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

Determinants of Lipid Domain Size

Saitov

Kalutsky

Galimzyanov

et al. 2022

IJMS

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“…Lipids with light-sensitive conformations allow switching between lipid-ordered and lipid-disordered domains (Saitov et al 2020). Concerning mechanosensitive channels, photoswitchable lipids pave the way for gating ion channels by light, which we recently demonstrated on the model channel gramicidin A (Pfeffermann et al 2021a).…”

Section: Membrane Mechanicsmentioning

confidence: 94%

Biophysical Reviews’ “Meet the Councilor Series”—a profile of Peter Pohl

Pohl

2021

Biophys Rev

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It is my pleasure to write a few words to introduce myself to the readers of Biophysical Reviews as part of the “Meet the Councilor Series.” Currently, I am serving the second period as IUPAB councilor after having been elected first in 2017. Initially, I studied Biophysics in Moscow (Russia) and later Medicine in Halle (Germany). My scientific carrier took me from the Medical School of the Martin Luther University of Halle-Wittenberg, via the Leibniz Institute for Molecular Pharmacology (Berlin) and the Institute for Biology at the Humboldt University (Berlin) to the Physics Department of the Johannes Kepler University in Linz (Austria). My key research interests lie in the molecular mechanisms of transport phenomena occurring at the lipid membrane, including (i) spontaneous and facilitated transport of water and other small molecules across membranes in reconstituted systems, (ii) proton migration along the membrane surface, (iii) protein translocation, and (iv) bilayer mechanics. Training of undergraduate, graduate, and postdoctoral researchers from diverse academic disciplines has been—and shall remain—a consistent part of my work.

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“…To obtain quantitative results, we utilized the following values of the membrane elastic parameters, typical for diphytanoylphosphatidylcholine (DPhPC): splay modulus B = 14 k B T ( k B T ≈ 4 × 10 −21 J) [ 62 ]; tilt modulus K t = 40 mN/m = 10 k B T /nm 2 [ 54 ]; the modulus of lateral stretching-compression K a = 133 mN/m [ 63 ]; twist modulus K rot = B /2 = 7 k B T ; the modulus of the Gaussian splay K G = − B /2 = −7 k B T [ 64 ]; spontaneous curvature J 0 = −0.015 nm −1 ; hydrophobic thickness h = 1.4 nm [ 42 , 63 ]; all values are related to the lipid monolayer. The length and the radius of the gramicidin monomer were h p = 0.75 nm and r 0 = 1 nm, respectively [ 34 , 35 , 36 ].…”

Section: Methodsmentioning

confidence: 99%

“…In turn, elastic parameters of the membrane (thickness, spontaneous curvature, lateral tension, elastic rigidity) substantially affect the characteristics of the channel (lifetime and probability of formation) [ 37 , 38 , 39 ]. This allowed utilizing gramicidin as a molecular sensor of membrane elasticity [ 40 , 41 , 42 ]. Various membrane-deforming inclusions, like amphipathic peptides, are also expected to influence the lifetime and probability of formation of the conducting channel via deformation-mediated lateral interactions with gA monomers, dimers and coaxial pairs.…”

Section: Introductionmentioning

confidence: 99%

Regulation of Antimicrobial Peptide Activity via Tuning Deformation Fields by Membrane-Deforming Inclusions

Kondrashov

Akimov

2021

IJMS

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Antimicrobial peptides (AMPs) are considered prospective antibiotics. Some AMPs fight bacteria via cooperative formation of pores in their plasma membranes. Most AMPs at their working concentrations can induce lysis of eukaryotic cells as well. Gramicidin A (gA) is a peptide, the transmembrane dimers of which form cation-selective channels in membranes. It is highly toxic for mammalians as being majorly hydrophobic gA incorporates and induces leakage of both bacterial and eukaryotic cell membranes. Both pore-forming AMPs and gA deform the membrane. Here we suggest a possible way to reduce the working concentrations of AMPs at the expense of application of highly-selective amplifiers of AMP activity in target membranes. The amplifiers should alter the deformation fields in the membrane in a way favoring the membrane-permeabilizing states. We developed the statistical model that allows describing the effect of membrane-deforming inclusions on the equilibrium between AMP monomers and cooperative membrane-permeabilizing structures. On the example of gA monomer-dimer equilibrium, the model predicts that amphipathic peptides and short transmembrane peptides playing the role of the membrane-deforming inclusions, even in low concentration can substantially increase the lifetime and average number of gA channels.

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Photoswitching of model ion channels in lipid bilayers

Cited by 23 publications

References 55 publications

Determinants of Lipid Domain Size

Determinants of Lipid Domain Size

Biophysical Reviews’ “Meet the Councilor Series”—a profile of Peter Pohl

Regulation of Antimicrobial Peptide Activity via Tuning Deformation Fields by Membrane-Deforming Inclusions

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