Conductance Switching in the Photoswitchable Protein Dronpa

Korpany, Katalin V.; Langat, Pinky; Kim, Dong Myeong; Edelman, Neil; Cooper, Daniel R.; Nadeau, Jay L.; Blum, Amy Szuchmacher

doi:10.1021/ja306031n

Cited by 18 publications

(18 citation statements)

References 27 publications

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“…[69][70][71] Biomolecular function (e.g. GFP electronic excitation [69][70][71]72 ) can indeed be used to modulate conductance, and proteins have been observed to act as molecular gates. 31,[73][74] To facilitate such work, we engineered a sfGFP variant with two CNTanchoring azide handles on opposite faces of the protein (Figure 6a).…”

Section: Z-scales= 6nmmentioning

confidence: 99%

Site-Specific One-to-One Click Coupling of Single Proteins to Individual Carbon Nanotubes: A Single-Molecule Approach

et al. 2017

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We report the site-specific coupling of single proteins to individual carbon nanotubes (CNTs) in solution and with single-molecule control. Using an orthogonal Click reaction, Green Fluorescent Protein (GFP) was engineered to contain a genetically encoded azide group and then bound to CNT ends in different configurations: in close proximity or at longer distances from the GFP's functional center. Atomic force microscopy and fluorescence analysis in solution and on surfaces at the single-protein level confirmed the importance of bioengineering optimal protein attachment sites to achieve direct protein-nanotube communication and bridging.

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Section: Z-scales= 6nmmentioning

confidence: 99%

Site-Specific One-to-One Click Coupling of Single Proteins to Individual Carbon Nanotubes: A Single-Molecule Approach

et al. 2017

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“…When proteins are contacted by metal electrodes, the situation is more complicated (5, 6). Single-protein conductances of nanosiemens (nS) over nanometer (nm) distances have been reported (7), with essentially the same conductance measured across a 2-nm protein (8) as across a 5.4-nm protein (9); temperature-independent transport has been observed (10) and siemens per meter conductivities over micrometers have been reported in bacterial pili (11, 12). Carrier injection via a contact is extremely sensitive to surface charge at the interface, with different preparations of oxide barrier at a semiconductor interface being the determining factor in whether electron transport in bacteriorhodopsin is temperature dependent or not (13).…”

mentioning

confidence: 90%

Role of contacts in long-range protein conductance

Zhang

Song

Pang

et al. 2019

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

175

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Proteins are widely regarded as insulators, despite reports of electrical conductivity. Here we use measurements of single proteins between electrodes, in their natural aqueous environment to show that the factor controlling measured conductance is the nature of the electrical contact to the protein, and that specific ligands make highly selective electrical contacts. Using six proteins that lack known electrochemical activity, and measuring in a potential region where no ion current flows, we find characteristic peaks in the distributions of measured single-molecule conductances. These peaks depend on the contact chemistry, and hence, on the current path through the protein. In consequence, the measured conductance distribution is sensitive to changes in this path caused by ligand binding, as shown with streptavidin–biotin complexes. Measured conductances are on the order of nanosiemens over distances of many nanometers, orders of magnitude more than could be accounted for by electron tunneling. The current is dominated by contact resistance, so the conductance for a given path is independent of the distance between electrodes, as long as the contact points on the protein can span the gap between electrodes. While there is no currently known biological role for high electronic conductance, its dependence on specific contacts has important technological implications, because no current is observed at all without at least one strongly bonded contact, so direct electrical detection is a highly selective and label-free single-molecule detection method. We demonstrate single-molecule, highly specific, label- and background free-electronic detection of IgG antibodies to HIV and Ebola viruses.

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“…Residue specific attachment of GFP to SWCNTs side-walls. Autofluorescent proteins such as green fluorescent protein (GFP; Figure 1b) are of particular current interest in the nanosciences as they are finding uses outside classical cell biology in areas ranging from optically gated transistors 32 , LEDs through stimulated emission 33,34 and as light capture and energy transfer devices 35 , such as for use in solar cell systems. They have particular advantages over organic molecules, not least because of their eco-friendly nature but that the protein encases the chromophore protecting it from the external environment and allowing modulation of its electronic properties through engineered changes in coupled bond networks.…”

Section: Resultsmentioning

confidence: 99%

Site-Specific Protein Covalent Attachment to Nanotubes and Its Electronic Impact on Single Molecule Function

Beachey¹,

Worthy²,

Jamieson³

et al. 2019

Preprint

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<p>Functional integration of proteins with carbon-based nanomaterials such as nanotubes holds great promise in emerging electronic and optoelectronic applications. Control over protein attachment poses a major challenge for consistent and useful device fabrication, especially when utilizing single/few molecule properties. Here, we exploit genetically encoded phenyl azide photochemistry to define the direct covalent attachment of three different proteins, including the fluorescent protein GFP, to carbon nanotube side walls. Single molecule fluorescence revealed that on attachment to SWCNTs GFP’s fluorescence changed in terms of intensity and improved resistance to photobleaching; essentially GFP is fluorescent for much longer on attachment. The site of attachment proved important in terms of electronic impact on GFP function, with the attachment site furthest from the functional center having the larger effect on fluorescence. Our approach provides a versatile and general method for generating intimate protein-CNT hybrid bioconjugates. It can be potentially applied easily to any protein of choice; attachment position and thus interface characteristics with the CNT can easily be changed by simply placing the phenyl azide chemistry at different residues by gene mutagenesis. Thus, our approach will allow consistent construction and modulate functional coupling through changing the protein attachment position.</p>

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Conductance Switching in the Photoswitchable Protein Dronpa

Abstract: Dronpa, a photoswitchable GFP-like protein, was self-assembled onto gold substrates, and its conductance was measured using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS).

Cited by 18 publications

References 27 publications

Site-Specific One-to-One Click Coupling of Single Proteins to Individual Carbon Nanotubes: A Single-Molecule Approach

Site-Specific One-to-One Click Coupling of Single Proteins to Individual Carbon Nanotubes: A Single-Molecule Approach

Role of contacts in long-range protein conductance

Site-Specific Protein Covalent Attachment to Nanotubes and Its Electronic Impact on Single Molecule Function

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