Label-free and charge-sensitive dynamic imaging of lipid membrane hydration on millisecond time scales

Tarun, Orly B.; Hannesschläger, Christof; Pohl, Peter; Roke, Sylvie

doi:10.1073/pnas.1719347115

Cited by 45 publications

(65 citation statements)

References 49 publications

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“…For this reason, a surface in contact with water exhibits a SH response that arises predominantly from the reorientation of water 35 – 47 . This reasoning is general, and the SH response of water has been used to determine the membrane potential of liposomes 37 , and free-standing lipid membranes in aqueous solutions that were subject to different external potentials 48 . Coupling these results from physics to neuroscience and using the fact that electrical signaling occurs through the working of ion channels, together with the assumption that the working of these ion channels can be modeled accurately by the GHK equation (Eq.…”

Section: Resultsmentioning

confidence: 99%

Membrane water for probing neuronal membrane potentials and ionic fluxes at the single cell level

et al. 2018

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Neurons communicate through electrochemical signaling within a complex network. These signals are composed of changes in membrane potentials and are traditionally measured with the aid of (toxic) fluorescent labels or invasive electrical probes. Here, we demonstrate an improvement in label-free second harmonic neuroimaging sensitivity by ~3 orders of magnitude using a wide-field medium repetition rate illumination. We perform a side-by-side patch-clamp and second harmonic imaging comparison to demonstrate the theoretically predicted linear correlation between whole neuron membrane potential changes and the square root of the second harmonic intensity. We assign the ion induced changes to the second harmonic intensity to changes in the orientation of membrane interfacial water, which is used to image spatiotemporal changes in the membrane potential and K+ ion flux. We observe a non-uniform spatial distribution and temporal activity of ion channels in mouse brain neurons.

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Section: Resultsmentioning

confidence: 99%

Membrane water for probing neuronal membrane potentials and ionic fluxes at the single cell level

et al. 2018

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“…Assessment by NMR spectroscopy revealed that water reorientation and translation are 3–5 times slower than in the bulk. 16 , 17 The level of mobility reduction is highly heterogeneous at the surface of lipid bilayers 18 and proteinaceous structures. That is, the dynamics of water reproduce the chemical features of amino acids.…”

Section: Water At Interfacesmentioning

confidence: 99%

Single-file transport of water through membrane channels

2018

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Water at interfaces governs many processes on the molecular scale from electrochemical and enzymatic reactions to protein folding. Here we focus on water transport through proteinaceous pores that are so narrow that the water molecules cannot overtake each other in the pore. After a short introduction into the single-file transport theory, we analyze experiments in which the unitary water permeability, p f , of water channel proteins (aquaporins, AQPs), potassium channels (KcsA), and antibiotics (gramicidin-A derivatives) has been obtained. A short outline of the underlying methods (scanning electrochemical microscopy, fluorescence correlation spectroscopy, measurements of vesicle light scattering) is also provided. We conclude that p f increases exponentially with a decreasing number N H of hydrogen bond donating or accepting residues in the channel wall. The variance in N H is responsible for a more than hundredfold change in p f . The dehydration penalty at the channel mouth has a smaller effect on p f . The intricate link between p f and the Gibbs activation energy barrier, DG ‡ t , for water flow suggests that conformational transitions of water channels act as a third determinant of p f .

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“…However, limitations arise due to the complexity of membranes. For instance, membranes are dynamic environments in constant change, lipid rearrangement occurs in milliseconds [163] , [164] and due to membranes being very thin, high-resolution techniques such as Nuclear Magnetic Resonance (NMR), Electron Paramagnetic Resonance (EPR) and fluorescence quenching are required [165] .…”

Section: Computational Target Fishing For the Study Of The Lp-membranmentioning

confidence: 99%

The ecological roles of microbial lipopeptides: Where are we going?

Gutiérrez-Chávez

Benaud

Ferrari

2021

Computational and Structural Biotechnology Journal

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Lipopeptides (LPs) are secondary metabolites produced by a diversity of bacteria and fungi. Their unique chemical structure comprises both a peptide and a lipid moiety. LPs are of major biotechnological interest owing to their emulsification, antitumor, immunomodulatory, and antimicrobial activities. To date, these versatile compounds have been applied across multiple industries, from pharmaceuticals through to food processing, cosmetics, agriculture, heavy metal, and hydrocarbon bioremediation. The variety of LP structures and the diversity of the environments from which LP-producing microorganisms have been isolated suggest important functions in their natural environment. However, our understanding of the ecological role of LPs is limited. In this review, the mode of action and the role of LPs in motility, antimicrobial activity, heavy metals removal and biofilm formation are addressed. We include discussion on the need to characterise LPs from a diversity of microorganisms, with a focus on taxa inhabiting ‘extreme’ environments. We introduce the use of computational target fishing and molecular dynamics simulations as powerful tools to investigate the process of interaction between LPs and cell membranes. Together, these advances will provide new understanding of the mechanism of action of novel LPs, providing greater insights into the roles of LPs in the natural environment.

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Label-free and charge-sensitive dynamic imaging of lipid membrane hydration on millisecond time scales

Cited by 45 publications

References 49 publications

Membrane water for probing neuronal membrane potentials and ionic fluxes at the single cell level

Membrane water for probing neuronal membrane potentials and ionic fluxes at the single cell level

Single-file transport of water through membrane channels

The ecological roles of microbial lipopeptides: Where are we going?

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