Photoinduced Electron Transfer Elicits a Change in the Static Dielectric Constant of a <i>de Novo</i> Designed Protein

Polizzi, Nicholas F.; Eibling, Matthew J.; Pérez-Aguilar, José Manuel; Rawson, Jeff; Lanci, Christopher J.; Fry, H. Christopher; Beratan, David N.; Saven, Jeffery G.; Therien, Michael J.

doi:10.1021/jacs.5b13180

Cited by 25 publications

(33 citation statements)

References 28 publications

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“…These milestones certainly necessitate the advent of new protein design and self-assembly strategies, a better understanding of protein structure/function/dynamics relationships and an improved command of protein–metal interactions. Smaller, synthetic metalloproteins can undoubtedly provide useful guidance in this regard. , Finally, we have learned in our studies that directed evolution and high-throughput selection strategies can lead to functional solutions and insights that would have been difficult to find through rational design. This emphasizes the important need for the proper design of functional screens or in vivo selection systems that could enable the evolution of multicomponent/multifunctional protein architectures.…”

Section: Discussionmentioning

confidence: 99%

Design and Construction of Functional Supramolecular Metalloprotein Assemblies

Churchfield

Tezcan

2019

Acc. Chem. Res.

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CONSPECTUS: Nature puts to use only a small fraction of metal ions in the periodic table. Yet, when incorporated into protein scaffolds, this limited set of metal ions carry out innumerable cellular functions and execute essential biochemical transformations such as photochemical H 2 O oxidation, O 2 or CO 2 reduction, and N 2 fixation, highlighting the outsized importance of metalloproteins in biology. Not surprisingly, elucidating the intricate interplay between metal ions and protein structures has been the focus of extensive structural and mechanistic scrutiny over the last several decades. As a result of such top-down efforts, we have gained a reasonably detailed understanding of how metal ions shape protein structures and how protein structures in turn influence metal reactivity. It is fair to say that we now have some idea−and in some cases, a good idea−about how most known metalloproteins function and we possess enough insight to quickly assess the modus operandi of newly discovered ones. However, translating this knowledge into an ability to construct functional metalloproteins from scratch represents a challenge at a whole different level: it is one thing to know how an automobile works; it is another to build one. In our quest to build new metalloproteins, we have taken an original approach in which folded, monomeric proteins are used as ligands or synthons for building supramolecular complexes through metal-mediated self-assembly (MDPSA, Metal-Directed Protein Self-Assembly). The interfaces in the resulting protein superstructures are subsequently tailored with covalent, noncovalent, or additional metal-coordination interactions for stabilization and incorporation of new functionalities (MeTIR, Metal Templated Interface Redesign). In an earlier Account, we had described the proof-of-principle studies for MDPSA and MeTIR, using a four-helix bundle, heme protein cytochrome cb 562 (cyt cb 562 ), as a model building block. By the end of those studies, we were able to demonstrate that a tetrameric, Zn-directed cyt cb 562 complex (Zn 4 :M1 4 ) could be stabilized through computationally prescribed noncovalent interactions inserted into the nascent protein−protein interfaces. In this Account, we first describe the rationale and motivation for our particular metalloprotein engineering strategy and a brief summary of our earlier work. We then describe the next steps in the "evolution" of bioinorganic complexity on the Zn 4 :M1 4 scaffold, namely, (a) the generation of a self-standing protein assembly that can stably and selectively bind metal ions, (b) the creation of reactive metal centers within the protein assembly, and (c) the coupling of metal coordination and reactivity to external stimuli through allosteric effects.

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Section: Discussionmentioning

confidence: 99%

Design and Construction of Functional Supramolecular Metalloprotein Assemblies

Churchfield

Tezcan

2019

Acc. Chem. Res.

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“…To directly determine the effective dielectric environment within a protein interior that mediates photoinduced electron transfer of a donor-bridge-acceptor molecule, we computationally designed a 4-helix bundle to bind the donor-bridge-acceptor molecule PZn-Ph-NDI (Figure 5, A and B). [16] We measured the impact of dielectric environment on photoinduced CS by studying electron transfer in a wide range of solvents (Figure 5, C), and found that the dielectric environment characteristic of the 4-helix bundle was unique: it could not be described by a single static dielectric constant (ε S ). To appropriately describe the CS and CR dynamics that occur in the protein bundle, the effective dielectric of CS was ε S ~ 9, whereas that of CR was ε S ~ 3.…”

Section: Applicationsmentioning

confidence: 99%

“…However, a mechanism to speed CS (that occurs in the Marcus normal regime) and slow charge recombination (that occurs in the Marcus inverted regime) would be to switch between a high and low dielectric environment before and after the CS event. To directly determine the effective dielectric environment within a protein interior that mediates photoinduced electron transfer of a donor‐bridge‐acceptor molecule, we computationally designed a 4‐helix bundle to bind the donor‐bridge‐acceptor molecule PZn‐Ph‐NDI (Figure , A and B) . We measured the impact of dielectric environment on photoinduced CS by studying electron transfer in a wide range of solvents (Figure , C), and found that the dielectric environment characteristic of the 4‐helix bundle was unique: it could not be described by a single static dielectric constant (ϵ S ).…”

Section: Applicationsmentioning

confidence: 99%

Mean First‐Passage Times in Biology

Polizzi

Therien

Beratan

2016

Israel Journal of Chemistry

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Many biochemical processes, such as charge hopping or protein folding, can be described by an average timescale to reach a final state, starting from an initial state. Here, we provide a pedagogical treatment of the mean first-passage time (MFPT) of a physical process, which depends on the number of intervening states between the initial state and the target state. Our aim in this tutorial review is to provide a clear development of the mean first-passage time formalism and to show some of its practical utility. The MFPT treatment can provide a useful link between microscopic rates and the average timescales often probed by experiment.

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“…General approaches to control redox balance and redox reactions in the cell are, in most cases, administering a dose of redox reagents to a cell or genetic modification aimed at controlling the activity of redox related enzymes. [4][5][6][7][8] Although these are promising approaches and some have already been approved for clinical applications, potential weak points include the fact that they lack sitespecificity in the cell and a longer time lag between the treatment and response compared to light control methods.…”

Section: Introductionmentioning

confidence: 99%

“…Utilizing a photoinduced electron transfer (ET) reaction from an artificial molecule can be an effective way modulating cellular redox reactions via photocontrol. 8,9 It is known that superoxide (O 2 − ) is generated as a result of biological ET reactions, and O 2 − from mitochondria triggers a variety of activities in a cell, including apoptotic cell death, 10,11 cell transformations, 12 or the regulation of cardiac rhythm. 13 Although KillerRed and certain porphyrin derivatives have been proposed as effective photosensitizers for generating O 2 − in the cell, 14,15 the generation of singlet oxygen ( 1 O 2 ), which can be formed via intermolecular energy transfer from a photoexcited sensitizer to 3 O 2 would potentially accompany the illumination of the sensitizers.…”

Section: Introductionmentioning

confidence: 99%

Optical control of mitochondrial reductive reactions in living cells using an electron donor–acceptor linked molecule

et al. 2017

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It has been known for decades that intracellular redox reactions control various vital functions in living systems, which include the synthesis of biomolecules, the modulation of protein functions, and cell signaling. Although there have been several reports on the control of such functions using DNA and RNA, the non-invasive optical control of biological functions is an important ongoing challenge. In this study, a hybrid of an electron donor-acceptor linked molecule based on a ferrocene(Fc)-porphyrin(ZnP)-fullerene(C) analogue and an elaborately designed nano-carrier, referred to herein as a MITO-Porter, resulted in a successful photoinduced intermolecular electron transfer reaction via the long-lived intramolecular charge separation, leading to site-specific reductive reactions in the mitochondria of living HeLa cells. A Fc-ZnP-C linked molecule, 1-Oct, was designed and prepared for taking advantage of the unique photophysical properties with excellent efficiency (i.e. a long lifetime and a high quantum yield) for photoinduced charge separation. The targeted delivery of 1-Oct to mitochondria was accomplished by using a combination of the Fc-ZnP-C molecule and a drug delivery nano-carrier, MITO-Porter, that was recently established by our group for intracellular cargo delivery. The successful delivery of 1-Oct by the MITO-Porter permitted the optically-controlled generation of O in the mitochondria of HeLa cells and the following induction of apoptosis as a cell signalling response was observed in confocal laser microscopy experiments. The obtained results indicate the use of an electron donor-acceptor system such as this can be a promising tool for the non-invasive triggering of redox-coupled cellular activities in living systems.

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Photoinduced Electron Transfer Elicits a Change in the Static Dielectric Constant of a de Novo Designed Protein

Cited by 25 publications

References 28 publications

Design and Construction of Functional Supramolecular Metalloprotein Assemblies

Design and Construction of Functional Supramolecular Metalloprotein Assemblies

Mean First‐Passage Times in Biology

Optical control of mitochondrial reductive reactions in living cells using an electron donor–acceptor linked molecule

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