Analysis of light-induced transmembrane ion gradients and membrane potential in Photosystem I proteoliposomes

Pennisi, Cristian Pablo; Greenbaum, Elias; Yoshida, Ken

doi:10.1016/j.bpc.2009.09.013

Cited by 9 publications

(7 citation statements)

References 59 publications

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“…To first order, the mechanism of the current change due to modulation in the cell membrane potential is explained by considering the primary process of the light-induced photosynthetic proton flux in the thylakoid membrane. In the presence of light, the protons are transported into the thylakoid lumen as a result of photosynthesis and slowly return to the stroma after the light is OFF . A schematic of the photosynthetic process pertinent to the biogating process is described in the SI (Figure C).…”

Section: Resultssupporting

confidence: 83%

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Noninvasive Measurement of Membrane Potential Modulation in Microorganisms: Photosynthesis in Green Algae

Lee

Saraf

2013

ACS Nano

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Cell membrane potential (CMP) modulation is a physical measurement to quantitatively probe cell physiology in real time at high specificity. Electrochemical field effect transistors (eFETs) made from graphene and Si nanowire provide strong mechanical and electrical coupling with neurons and muscle cells to noninvasively measure CMP at high sensitivity. To date, there are no noninvasive methods to study electrophysiology of microorganisms because of stiff cell walls and significantly smaller membrane polarizations. An eFET made from the smallest possible nanostructure, a nanoparticle, with sensitivity to a single-electron charge is developed to noninvasively measure CMP modulation in algae. The applicability of the device is demonstrated by measuring CMP modulation due to a light-induced proton gradient inside the chloroplast during photosynthesis. The ∼9 mV modulation in CMP in algae is consistent with the absorbance spectrum of chlorophyll, photosynthetic pathway, and inorganic carbon source concentration in the environment. The method can potentially become a routine method to noninvasively study electrophysiology of cells, such as microorganisms for biofuels.

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Section: Resultssupporting

confidence: 83%

“…(A complication in quantifying electrophysiology studies where there is significant ion flux makes the method model dependent) . Thus, from the model (eq (10) in SI), ΔpH ≈ 0.97, which is consistent with the literature …”

Section: Resultsmentioning

confidence: 61%

Noninvasive Measurement of Membrane Potential Modulation in Microorganisms: Photosynthesis in Green Algae

Lee

Saraf

2013

ACS Nano

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“…Previous work indicates that at high valinomycin concentrations beginning at~100 nM, membrane H þ /OH À permeability increases sharply with increasing valinomycin concentration (16,(42)(43)(44). At these elevated concentrations, valinomycin is therefore thought to display protonophoric activity in addition to ferrying K þ ions (42,43,45); in 2006, K rí z et al provided NMR evidence for the existence of an H 3 O þ -carrying valinomycin complex, reinforcing this conclusion (46,47). We decided to experimentally establish an appropriate valinomycin concentration for the system by measuring the H þ /OH À permeability of POPC vesicles at different valinomycin concentrations.…”

Section: Resultsmentioning

confidence: 89%

Effects of Lipid Tethering in Extremophile-Inspired Membranes on H + /OH − Flux at Room Temperature

Schroeder

Leriche

Koyanagi

et al. 2016

Biophysical Journal

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This work explores the proton/hydroxide permeability (PH+/OH-) of membranes that were made of synthetic extremophile-inspired phospholipids with systematically varied structural elements. A fluorescence-based permeability assay was optimized to determine the effects on the PH+/OH- through liposome membranes with variations in the following lipid attributes: transmembrane tethering, tether length, and the presence of isoprenoid methyl groups on one or both lipid tails. All permeability assays were performed in the presence of a low concentration of valinomycin (10 nM) to prevent buildup of a membrane potential without artificially increasing the measured PH+/OH-. Surprisingly, the presence of a transmembrane tether did not impact PH+/OH- at room temperature. Among tethered lipid monolayers, PH+/OH- increased with increasing tether length if the number of carbons in the untethered acyl tail was constant. Untethered lipids with two isoprenoid methyl tails led to lower PH+/OH- values than lipids with only one or no isoprenoid tails. Molecular dynamics simulations revealed a strong positive correlation between the probability of observing water molecules in the hydrophobic core of these lipid membranes and their proton permeability. We propose that water penetration as revealed by molecular dynamics may provide a general strategy for predicting proton permeability through various lipid membranes without the need for experimentation.

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“…The main conclusion was that this configuration would not be suitable for fast cell activation due to the slow onset of the potential [20]. Additionally, we have developed a methodology to detect PSI insertion, showing for the first time that mammalian cell membranes are a reasonable accommodating environment for PSI [21].…”

Section: Molecular Photovoltaic Structures For Optical Activation Of mentioning

confidence: 98%

Molecular photovoltaic structures for optical activation of excitable cells: current advances and perspectives

Pennisi

2010

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology

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Current neural stimulation devices for the treatment of sensory and motor disorders are based on electrical stimulation. Using this technique, neural activity is triggered by electrical stimuli applied through electrodes in contact with the cells. Due to physical constraints of the electrodes the spatial control of stimulation is limited, which in some cases generates unwanted side effects. In addition, adverse tissue reactions occur after long term contact with the electrodes. A potential solution is the application of methods based on light instead of electrical energy, in which the electrical stimulator and the electrode are replaced by a light source and an optical fiber. Although optical stimulation approaches that allow spatially selective, highly specific and contact-free control of the neural activity have been developed in recent years, their implementation requires genetic manipulation, limiting the perspectives for clinical applications. A molecular photovoltaic structure potentially able to mediate light-induced cellular responses without involving genetic modification is the photosynthetic pigment-protein complex Photosystem I (PSI). In this work, the recent advances on the application of PSI reaction centers for optical control of cellular activity are presented. Perspectives of application of PSI reaction centers in the development of future methods for clinical neural stimulation are also presented.

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Analysis of light-induced transmembrane ion gradients and membrane potential in Photosystem I proteoliposomes

Cited by 9 publications

References 59 publications

Noninvasive Measurement of Membrane Potential Modulation in Microorganisms: Photosynthesis in Green Algae

Noninvasive Measurement of Membrane Potential Modulation in Microorganisms: Photosynthesis in Green Algae

Effects of Lipid Tethering in Extremophile-Inspired Membranes on H + /OH − Flux at Room Temperature

Molecular photovoltaic structures for optical activation of excitable cells: current advances and perspectives

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