The Gramicidin‐Based Biosensor: A Functioning Nano‐Machine

Cornell, Bruce; Braach-Maksvytis, Vijoleta; King, Laurie A.; Osman, Péter; Raguse, Burkhard; Wieczorek, Lech; Pace, Ronald

doi:10.1002/9780470515716.ch15

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…Derivatives of gramicidin A (gA) show promise as ultrasensitive transducers for detecting chemical and biochemical analytes because of the high amplification that is inherent to the ion channel activity of these helical peptides: − the opening of a single ion channel results in the measurable flux of 10 3 to 10 6 ions per millisecond across lipid membranes . Gramicidin A is a natural ion channel-forming peptide (MW 1.9 kDa, secreted by the bacterium Bacillus brevis ) that facilitates a transmembrane flux of monovalent cations upon reversible head-to-head dimerization in lipid bilayers. , Gramicidin A is well suited for biosensor applications because of its defined and quantized characteristics of ion channel conductance.…”

Section: Introductionmentioning

confidence: 99%

Designing Nanosensors Based on Charged Derivatives of Gramicidin A

et al. 2007

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Detection of chemical processes on a single molecule scale is the ultimate goal of sensitive analytical assays. We recently reported the possibility to detect chemical modifications on individual molecules by monitoring a change in the single ion channel conductance of derivatives of gramicidin A (gA) upon reaction with analytes in solution. These peptide-based nanosensors detect reaction-induced changes in the charge of gA derivatives that were engineered to carry specific functional groups near their C-terminus.1 Here, we discuss five key design parameters to optimize the performance of such chemomodulated ion channel sensors. In order to realize an effective sensor that measures changes in charge of groups attached to the C-terminus of a gA pore, the following conditions should be fulfilled: (1) the change in charge should occur as close to the entrance of the pore as possible; (2) the charge before and after reaction should be well-defined within the operational pH range; (3) the ionic strength of the recording buffer should be as low as possible while maintaining a detectable flow of ions through the pore; (4) the applied transmembrane voltage should be as high as possible while maintaining a stable membrane; (5) the lipids in the supporting membrane should either be zwitterionic or charged differently than the derivative of gA. We show that under the condition of high applied transmembrane potential (>100 mV) and low ionic strength of the recording buffer (< or =0.10 M), a change in charge at the entrance of the pore is the dominant requirement to distinguish between two differently charged derivatives of gA; the conductance of the heterodimeric gA pore reported here does not depend on a difference in charge at the exit of the pore. We provide a simple explanation for this asymmetric characteristic based on charge-induced local changes in the concentration of cations near the lipid bilayer membrane. Charge-based ion channel sensors offer tremendous potential for ultrasensitive functional detection since a single chemical modification of each individual sensing element can lead to readily detectable changes in channel conductance.

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Section: Introductionmentioning

confidence: 99%

Designing Nanosensors Based on Charged Derivatives of Gramicidin A

et al. 2007

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“…By far the most literature can be found for the membraneactive peptides alamethicin, valinomycin and gramicidin [166][167][168][169][170][171][172]. The last was also used to determine the fluidity of the lipid membrane and as a molecular force probe [173,174].…”

Section: Membrane-active Peptides and Integral Membrane Proteinsmentioning

confidence: 99%

Biomimetic interfaces based on S-layer proteins, lipid membranes and functional biomolecules

Schuster

Sleytr

2014

J. R. Soc. Interface.

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Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at mesoand macroscopic scale. In this review, we provide a state-of-the-art survey of how S-layer proteins, lipids and polymers may be used as basic building blocks for the assembly of S-layer-supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and, thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas in the (lab-on-a-) biochip technology are combining composite S-layer membrane systems involving specific membrane functions with the silicon world. Thus, it might become possible to create artificial noses or tongues, where many receptor proteins have to be exposed and read out simultaneously. Moreover, S-layer-coated liposomes and emulsomes copying virus envelopes constitute promising nanoformulations for the production of novel targeting, delivery, encapsulation and imaging systems.

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“…The known propensity of natural ionic channels to undergo specific regulation provides an opportunity for constructing a channel that can open and close in response to the introduction of certain analytes in the bathing solution. Most of the studies based on this principle utilize α-hemolysin (Bezrukov 2000, Bayley and Cremer 2001, Movileanu 2009, though some other channel formers, including gramicidin A (gA) and alamethicin, are also used (Cornell et al 1999, Woodhouse et al 1999, Suarez et al 1998, Futaki et al 2001b, 2001a, Hirano et al 2003, Zhang et al 2002, Futaki et al 2004, Blake et al 2006, Blake et al 2008, Capone et al 2007, Macrae et al 2009, Majd et al 2009.…”

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confidence: 99%

Mechanistic insight into gramicidin-based detection of protein–ligand interactions via sensitized photoinactivation

Rokitskaya

Macrae

Blake

et al. 2010

J. Phys.: Condens. Matter

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Among the many challenges for the development of ion channel-based sensors is the poor understanding of how to engineer modified transmembrane pores with tailored functionality that can respond to external stimuli. Here, we use the method of sensitized photoinactivation of gramicidin A (gA) channels in planar bilayer lipid membranes to help elucidate the underlying mechanistic details for changes in macroscopic transmembrane ionic current observed upon interaction of C-terminally attached gA ligands with specific proteins in solution. Three different systems were studied: (i) carbonic anhydrase (CA) and gA-sulfonamide, (ii) PSD-95 protein (belonging to the 'PDZ domain-containing protein') and a gA analog carrying the KGGHRRSARYLESSV peptide sequence at the C-terminus, and (iii) an anti-biotin antibody and gA-biotin. The results challenge a previously proposed mechanistic hypothesis suggesting that protein-induced current suppression is due to steric blockage of the ion passage through gA channels, while they reveal new insight for consideration in alternative mechanistic models. Additionally, we demonstrate that the length of a linker between the ligand and the gA channel may be less important for gramicidin-based detection of monovalent compared to multivalent protein-ligand interactions. These studies collectively shed new light on the mechanism of protein-induced current alterations in bilayer recordings of gA derivatives, which may be important in the design of new gramicidin-based sensors.

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The Gramicidin‐Based Biosensor: A Functioning Nano‐Machine

Cited by 8 publications

References 28 publications

Designing Nanosensors Based on Charged Derivatives of Gramicidin A

Designing Nanosensors Based on Charged Derivatives of Gramicidin A

Biomimetic interfaces based on S-layer proteins, lipid membranes and functional biomolecules

Mechanistic insight into gramicidin-based detection of protein–ligand interactions via sensitized photoinactivation

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