Visualization of coherent nuclear motion in a membrane protein by femtosecond spectroscopy

Vos, Marten H.; Rappaport, Fabrice; Lambry, Jean−Christophe; Breton, Jacques; Martin, Jean−Louis

doi:10.1038/363320a0

Cited by 551 publications

(470 citation statements)

References 38 publications

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“…This approximation was used to obtain a simple relation between time-dependent populations of exciton states, nonMarkovian optical lineshapes and pump-probe spectra. An inclusion of coherent vibrational motion found in some pigment-protein complexes [89][90][91][92][93][94] is beyond the scope of the present approach, which considers equilibrium fluctuations of the vibrations. A Markov approximation could have been used to include coherences between different exciton states.…”

Section: F Approximationsmentioning

confidence: 99%

On the relation of protein dynamics and exciton relaxation in pigment–protein complexes: An estimation of the spectral density and a theory for the calculation of optical spectra

Renger¹,

Marcus²

2002

The Journal of Chemical Physics

335

498

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A theory for calculating time-and frequency-domain optical spectra of pigment-protein complexes is presented using a density matrix approach. Non-Markovian effects in the excitonvibrational coupling are included. A correlation function is deduced from the simulation of 1.6 K fluorescence line narrowing spectra of a monomer pigment-protein complex ͑B777͒, and then used to calculate fluorescence line narrowing spectra of a dimer complex ͑B820͒. A vibrational sideband of an excitonic transition is obtained, a distinct non-Markovian feature, and agrees well with experiment on B820 complexes. The theory and the above correlation function are used elsewhere to make predictions and compare with data on time-domain pump-probe spectra and frequencydomain linear absorption, circular dichroism and fluorescence spectra of Photosystem II reaction centers.

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Section: F Approximationsmentioning

confidence: 99%

On the relation of protein dynamics and exciton relaxation in pigment–protein complexes: An estimation of the spectral density and a theory for the calculation of optical spectra

Renger¹,

Marcus²

2002

The Journal of Chemical Physics

335

498

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“…S3) reveals that initial energy dissipation takes on multiple yet less directional pathways. The coherent low-frequency modes originate from vibronic coupling and are likely ubiquitous in photoexcited environments (22,(39)(40)(41), similar to the case of photoacid pyranine in various solvents (31,(42)(43)(44)(45). Pyranine undergoes ESPT in water following photoexcitation (45), but ESPT is blocked in methanol and multiple low-frequency modes are observed (31).…”

Section: Structural Dynamics In the Chromophore Local Environment Formentioning

confidence: 99%

Excited-state structural dynamics of a dual-emission calmodulin-green fluorescent protein sensor for calcium ion imaging

Oscar

Liu

Zhao

et al. 2014

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

191

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Fluorescent proteins (FPs) have played a pivotal role in bioimaging and advancing biomedicine. The versatile fluorescence from engineered, genetically encodable FP variants greatly enhances cellular imaging capabilities, which are dictated by excited-state structural dynamics of the embedded chromophore inside the protein pocket. Visualization of the molecular choreography of the photoexcited chromophore requires a spectroscopic technique capable of resolving atomic motions on the intrinsic timescale of femtosecond to picosecond. We use femtosecond stimulated Raman spectroscopy to study the excited-state conformational dynamics of a recently developed FP-calmodulin biosensor, GEM-GECO1, for calcium ion (Ca 2+ ) sensing. This study reveals that, in the absence of Ca 2+ , the dominant skeletal motion is a ∼170 cm −1 phenol-ring in-plane rocking that facilitates excited-state proton transfer (ESPT) with a time constant of ∼30 ps (6 times slower than wild-type GFP) to reach the green fluorescent state. The functional relevance of the motion is corroborated by molecular dynamics simulations. Upon Ca 2+ binding, this in-plane rocking motion diminishes, and blue emission from a trapped photoexcited neutral chromophore dominates because ESPT is inhibited. Fluorescence properties of site-specific protein mutants lend further support to functional roles of key residues including proline 377 in modulating the H-bonding network and fluorescence outcome. These crucial structural dynamics insights will aid rational design in bioengineering to generate versatile, robust, and more sensitive optical sensors to detect Ca 2+ in physiologically relevant environments.calcium-sensing fluorescent protein | femtosecond Raman spectroscopy | fluorescence modulation mechanism | molecular movie G reen fluorescent protein (GFP) first emerged as a revolutionary tool for bioimaging and molecular and cellular biology about 20 years ago (1-3), and the quest to discover and engineer biosensors with improved and expanded functionality has yielded exciting advances. Recently, the color palette of genetically encoded Ca 2+ sensors for optical imaging (the GECO series) has been expanded to include blue, improved green, red intensiometric, and emission ratiometric sensors (4-7). The GECO proteins belong to the GCaMP family of Ca 2+ sensors that are chimeras of a circularly permutated (cp)GFP, calmodulin (CaM), and a peptide derived from myosin light chain kinase (M13) (8). The CaM unit undergoes large-scale structural changes upon Ca 2+ binding as it wraps around M13. These changes, especially at the interfacial region where CaM interacts with cpGFP, allosterically alter the local environment of the tyrosine-derived chromophore and lead to dramatic fluorescence change in the presence of Ca 2+ (9, 10). Because GCaMP and GECO proteins are genetically encodable, show sensitivity to physiologically relevant Ca 2+ concentrations, and respond to Ca 2+ concentration changes rapidly, they have gained increasing popularity for in vivo imaging of Ca 2+ in neur...

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“…In the vicinity of an optical resonance the refractive index of the crystal is strongly frequency-dependent, causing a femtosecond light pulse (not monochromatic through the Heisenberg uncertainty principle) to broaden as it propagates through the crystal, a phenomenon encountered in near-femtosecond spectroscopy experiments (19)(20)(21)(22)(23)(24)(25)(26) that is compensated for optically by focusing the minimum pulse duration at the center of the sample. Hence, dispersion of the laser pulse should not significantly limit the potential temporal resolution in x-ray diffraction experiments.…”

Section: Physical Crystalmentioning

confidence: 99%

“…Coherent reaction dynamics have been observed up to a few picoseconds following femtosecond photoexcitation (e.g., see ref. 23). Changes in magnitude of observed intensities across a single topogram depend on the size of the molecule and on the degree of the structural rearrangement.…”

Section: Crossed-beam Topographymentioning

confidence: 99%

“…With the advent of the femtosecond pulsed laser, several beautiful ultra-fast spectroscopy experiments have been performed on small molecules (19)(20)(21) as well as on biologically important macromolecules (22)(23)(24)(25)(26). These experiments have opened a window through which the behavior of chemical and biological systems can be studied at time scales characteristic of transition-state life times.…”

mentioning

confidence: 99%

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Femtosecond time resolution in x-ray diffraction experiments

Neutze

Hajdu

1997

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

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This paper presents the theoretical background for a synthesis of femtosecond spectroscopy and x-ray diffraction. When a diffraction quality crystal with 0.1-0.3 mm overall dimensions is photoactivated by a femtosecond laser pulse (physical length ‫؍‬ 0.3 m), the evolution of molecules at separated points in the crystal will not be simultaneous because a finite time is required for the laser pulse to propagate through the body of the crystal. Utilizing this lack of global crystal synchronization, topographic x-ray diffraction may enable femtosecond temporal resolution to be achieved from ref lection profiles in the diffraction pattern with x-ray exposures of picosecond or longer duration. Such x-ray pulses are currently available, and could be used to study femtosecond reaction dynamics at atomic resolution on crystals of both small-and macromolecules. A general treatment of excitation and diffraction geometries in relation to spatial and temporal resolution is presented.

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Visualization of coherent nuclear motion in a membrane protein by femtosecond spectroscopy

Cited by 551 publications

References 38 publications

On the relation of protein dynamics and exciton relaxation in pigment–protein complexes: An estimation of the spectral density and a theory for the calculation of optical spectra

On the relation of protein dynamics and exciton relaxation in pigment–protein complexes: An estimation of the spectral density and a theory for the calculation of optical spectra

Excited-state structural dynamics of a dual-emission calmodulin-green fluorescent protein sensor for calcium ion imaging

Femtosecond time resolution in x-ray diffraction experiments

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