Modification of the Optoelectronic Properties of Membranes via Insertion of Amphiphilic Phenylenevinylene Oligoelectrolytes

Garner, Logan E.; Park, Juhyun; Dyar, Scott M.; Chworoś, Arkadiusz; Sumner, James J.; Bazan, Guillermo C.

doi:10.1021/ja1016156

Cited by 136 publications

(268 citation statements)

References 92 publications

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“…As an intervening spacer, PPV molecular wires are an ideal choice because of their low attenuation values (26), synthetic tractability, and demonstrated ability to conduct current through lipid bilayers (31). Anilines are common PeT donors and the dialkyl groups should enhance uptake into the plasma membrane.…”

Section: Resultsmentioning

confidence: 99%

Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires

Miller¹,

Lin²,

Frady³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

284

323

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Fluorescence imaging is an attractive method for monitoring neuronal activity. A key challenge for optically monitoring voltage is development of sensors that can give large and fast responses to changes in transmembrane potential. We now present fluorescent sensors that detect voltage changes in neurons by modulation of photo-induced electron transfer (PeT) from an electron donor through a synthetic molecular wire to a fluorophore. These dyes give bigger responses to voltage than electrochromic dyes, yet have much faster kinetics and much less added capacitance than existing sensors based on hydrophobic anions or voltagesensitive ion channels. These features enable single-trial detection of synaptic and action potentials in cultured hippocampal neurons and intact leech ganglia. Voltage-dependent PeT should be amenable to much further optimization, but the existing probes are already valuable indicators of neuronal activity. F luorescence imaging can map the electrical activity and communication of multiple spatially resolved neurons and thus complements traditional electrophysiological measurements (1, 2). Ca 2+ imaging is the most popular of such techniques, because the indicators are well-developed (3-6), highly sensitive (5, 6), and genetically encodable (7-13), enabling investigation of the spatial distribution of Ca 2+ dynamics in structures as small as dendritic spines and as large as functional circuits. However, because neurons translate depolarizations into Ca 2+ signals via a complex series of pumps, channels, and buffers, fluorescence imaging of Ca 2+ transients cannot provide a complete picture of electrical activity in neurons. Observed Ca 2+ spikes are temporally low-pass filtered from the initial depolarization and provide limited information regarding hyperpolarizations and subthreshold events. Direct measurement of transmembrane potential with fluorescent indicators would provide a more accurate account of the timing and location of neuronal activity. Despite the promise of fluorescent voltage-sensitive dyes (VSDs), previous classes of VSDs have each been hampered by some combination of insensitivity, slow kinetics (14-16), heavy capacitative loading (17-21), lack of genetic targetability, or phototoxicity. Two of the more widely used classes of VSDs, electrochromic and FRET dyes, illustrate the problems associated with developing fast and sensitive fluorescent VSDs.Electrochromic dyes respond to voltage through a direct interaction between the chromophore and the electric field (Scheme 1A). This Stark effect leads to small wavelength shifts in the absorption and emission spectrum. Because the electric field directly modulates the energy levels of the chromophore, the kinetics of voltage sensing occur on a timescale commensurate with absorption and emission, resulting in ultrafast (fs to ps) hypso-or bathochromic shifts many orders-of-magnitude faster than required to resolve fast spiking events and action potentials in neurons. This small wavelength shift dictates that the fluorescence signal ...

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Section: Resultsmentioning

confidence: 99%

Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires

Miller¹,

Lin²,

Frady³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

284

323

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“…DSSNϩ, 1,4-bis(4Љ-(N,N-bis(6ЉЉ-(N,N,N-trimethylammonium)hexyl)amino)-styryl)benzene tetraiodide (DSBNϩ), and 1,4-bis(4Љ-(N,N-bis(6ЉЉ-(N,N,N-trimethylammonium)hexyl)amino)-styryl)-2,3,5,6 tetrafluorobenzene tetraiodide (4F-DSBNϩ) were synthesized as reported previously (2,11). The MIMs used in this study were selected because their biotechnological potential had been demonstrated previously in bioelectrochemical systems and because interesting interactions with microbial cells have been documented (1,3,10).…”

Section: Methodsmentioning

confidence: 99%

“…Nisin is an amphiphilic broad-spectrum cationic antimicrobial peptide produced by Streptococcus lactis that is active against Gram-positive bacteria and which has been widely used in the food industry since the 1960s (2). Microbes that have acquired resistance to nisin have bulk changes in their membrane phospholipid head group composition and have been shown to contain less DPG than their wild-type counterparts.…”

Section: Aminoacylated Phospholipidsmentioning

confidence: 99%

“…ligopolyphenylenevinylene-conjugated oligoelectrolytes (OPVCOEs) are a recently described class of membrane insertion molecules (MIMs) that target the microbial envelope with the specific aim of promoting charge transfer across microbial membranes and which potentially have a range of other biotechnological applications (1,2). OPV-COEs are amphipathic molecules consisting of a conjugated benzene ring backbone that is terminated with ionic pendant chains that have an affinity for biological membranes because of the charge distribution and amphiphilic nature of the molecule (see Fig.…”

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confidence: 99%

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Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria

Hinks

Poh

Chu

et al. 2015

Appl Environ Microbiol

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The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Grampositive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone.

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“…Electrode-driven reduction of carbon dioxide via acetogenic microorganisms, known as microbial electrosynthesis (13,14), is a strategy for conversion of CO 2 to organic commodities without a biomass intermediate. Biofilms of acetogenic microorganisms colonize surfaces of cathodes and directly convert CO 2 to organic products that are excreted from the cells.…”

mentioning

confidence: 99%

A Genetic System for Clostridium ljungdahlii: a Chassis for Autotrophic Production of Biocommodities and a Model Homoacetogen

Leang

Ueki

Nevin

et al. 2013

Appl Environ Microbiol

179

191

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Methods for genetic manipulation of Clostridium ljungdahlii are of interest because of the potential for production of fuels and other biocommodities from carbon dioxide via microbial electrosynthesis or more traditional modes of autotrophy with hydrogen or carbon monoxide as the electron donor. Furthermore, acetogenesis plays an important role in the global carbon cycle. Gene deletion strategies required for physiological studies of C. ljungdahlii have not previously been demonstrated. An electroporation procedure for introducing plasmids was optimized, and four different replicative origins for plasmid propagation in C. ljungdahlii were identified. Chromosomal gene deletion via double-crossover homologous recombination with a suicide vector was demonstrated initially with deletion of the gene for FliA, a putative sigma factor involved in flagellar biogenesis and motility in C. ljungdahlii. Deletion of fliA yielded a strain that lacked flagella and was not motile. To evaluate the potential utility of gene deletions for functional genomic studies and to redirect carbon and electron flow, the genes for the putative bifunctional aldehyde/alcohol dehydrogenases, adhE1 and adhE2, were deleted individually or together. Deletion of adhE1, but not adhE2, diminished ethanol production with a corresponding carbon recovery in acetate. The double deletion mutant had a phenotype similar to that of the adhE1-deficient strain. Expression of adhE1 in trans partially restored the capacity for ethanol production. These results demonstrate the feasibility of genetic investigations of acetogen physiology and the potential for genetic manipulation of C. ljungdahlii to optimize autotrophic biocommodity production.

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Modification of the Optoelectronic Properties of Membranes via Insertion of Amphiphilic Phenylenevinylene Oligoelectrolytes

Cited by 136 publications

References 92 publications

Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires

Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires

Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria

A Genetic System for Clostridium ljungdahlii: a Chassis for Autotrophic Production of Biocommodities and a Model Homoacetogen

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