Publications by authors named "Rita Graceffa"

15 Publications

  • Page 1 of 1

Evaluation of serial crystallographic structure determination within megahertz pulse trains.

Struct Dyn 2019 Nov 4;6(6):064702. Epub 2019 Dec 4.

Center for Free-Electron Laser Science, Deutsches Elektronen Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany.

The new European X-ray Free-Electron Laser (European XFEL) is the first X-ray free-electron laser capable of delivering intense X-ray pulses with a megahertz interpulse spacing in a wavelength range suitable for atomic resolution structure determination. An outstanding but crucial question is whether the use of a pulse repetition rate nearly four orders of magnitude higher than previously possible results in unwanted structural changes due to either radiation damage or systematic effects on data quality. Here, separate structures from the first and subsequent pulses in the European XFEL pulse train were determined, showing that there is essentially no difference between structures determined from different pulses under currently available operating conditions at the European XFEL.
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http://dx.doi.org/10.1063/1.5124387DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6892710PMC
November 2019

The Single Particles, Clusters and Biomolecules and Serial Femtosecond Crystallography instrument of the European XFEL: initial installation.

J Synchrotron Radiat 2019 May 12;26(Pt 3):660-676. Epub 2019 Apr 12.

European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.

The European X-ray Free-Electron Laser (FEL) became the first operational high-repetition-rate hard X-ray FEL with first lasing in May 2017. Biological structure determination has already benefitted from the unique properties and capabilities of X-ray FELs, predominantly through the development and application of serial crystallography. The possibility of now performing such experiments at data rates more than an order of magnitude greater than previous X-ray FELs enables not only a higher rate of discovery but also new classes of experiments previously not feasible at lower data rates. One example is time-resolved experiments requiring a higher number of time steps for interpretation, or structure determination from samples with low hit rates in conventional X-ray FEL serial crystallography. Following first lasing at the European XFEL, initial commissioning and operation occurred at two scientific instruments, one of which is the Single Particles, Clusters and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument. This instrument provides a photon energy range, focal spot sizes and diagnostic tools necessary for structure determination of biological specimens. The instrumentation explicitly addresses serial crystallography and the developing single particle imaging method as well as other forward-scattering and diffraction techniques. This paper describes the major science cases of SPB/SFX and its initial instrumentation - in particular its optical systems, available sample delivery methods, 2D detectors, supporting optical laser systems and key diagnostic components. The present capabilities of the instrument will be reviewed and a brief outlook of its future capabilities is also described.
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http://dx.doi.org/10.1107/S1600577519003308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510195PMC
May 2019

Initial observations of the femtosecond timing jitter at the European XFEL.

Opt Lett 2019 Apr;44(7):1650-1653

Intense, ultrashort, and high-repetition-rate X-ray pulses, combined with a femtosecond optical laser, allow pump-probe experiments with fast data acquisition and femtosecond time resolution. However, the relative timing of the X-ray pulses and the optical laser pulses can be controlled only to a level of the intrinsic error of the instrument which, without characterization, limits the time resolution of experiments. This limitation inevitably calls for a precise determination of the relative arrival time, which can be used after measurement for sorting and tagging the experimental data to a much finer resolution than it can be controlled to. The observed root-mean-square timing jitter between the X-ray and the optical laser at the SPB/SFX instrument at European XFEL was 308 fs. This first measurement of timing jitter at the European XFEL provides an important step in realizing ultrafast experiments at this novel X-ray source. A method for determining the change in the complex refractive index of samples is also presented.
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http://dx.doi.org/10.1364/OL.44.001650DOI Listing
April 2019

Megahertz serial crystallography.

Authors:
Max O Wiedorn Dominik Oberthür Richard Bean Robin Schubert Nadine Werner Brian Abbey Martin Aepfelbacher Luigi Adriano Aschkan Allahgholi Nasser Al-Qudami Jakob Andreasson Steve Aplin Salah Awel Kartik Ayyer Saša Bajt Imrich Barák Sadia Bari Johan Bielecki Sabine Botha Djelloul Boukhelef Wolfgang Brehm Sandor Brockhauser Igor Cheviakov Matthew A Coleman Francisco Cruz-Mazo Cyril Danilevski Connie Darmanin R Bruce Doak Martin Domaracky Katerina Dörner Yang Du Hans Fangohr Holger Fleckenstein Matthias Frank Petra Fromme Alfonso M Gañán-Calvo Yaroslav Gevorkov Klaus Giewekemeyer Helen Mary Ginn Heinz Graafsma Rita Graceffa Dominic Greiffenberg Lars Gumprecht Peter Göttlicher Janos Hajdu Steffen Hauf Michael Heymann Susannah Holmes Daniel A Horke Mark S Hunter Siegfried Imlau Alexander Kaukher Yoonhee Kim Alexander Klyuev Juraj Knoška Bostjan Kobe Manuela Kuhn Christopher Kupitz Jochen Küpper Janine Mia Lahey-Rudolph Torsten Laurus Karoline Le Cong Romain Letrun P Lourdu Xavier Luis Maia Filipe R N C Maia Valerio Mariani Marc Messerschmidt Markus Metz Davide Mezza Thomas Michelat Grant Mills Diana C F Monteiro Andrew Morgan Kerstin Mühlig Anna Munke Astrid Münnich Julia Nette Keith A Nugent Theresa Nuguid Allen M Orville Suraj Pandey Gisel Pena Pablo Villanueva-Perez Jennifer Poehlsen Gianpietro Previtali Lars Redecke Winnie Maria Riekehr Holger Rohde Adam Round Tatiana Safenreiter Iosifina Sarrou Tokushi Sato Marius Schmidt Bernd Schmitt Robert Schönherr Joachim Schulz Jonas A Sellberg M Marvin Seibert Carolin Seuring Megan L Shelby Robert L Shoeman Marcin Sikorski Alessandro Silenzi Claudiu A Stan Xintian Shi Stephan Stern Jola Sztuk-Dambietz Janusz Szuba Aleksandra Tolstikova Martin Trebbin Ulrich Trunk Patrik Vagovic Thomas Ve Britta Weinhausen Thomas A White Krzysztof Wrona Chen Xu Oleksandr Yefanov Nadia Zatsepin Jiaguo Zhang Markus Perbandt Adrian P Mancuso Christian Betzel Henry Chapman Anton Barty

Nat Commun 2018 10 2;9(1):4025. Epub 2018 Oct 2.

Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607, Hamburg, Germany.

The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a β-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source.
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http://dx.doi.org/10.1038/s41467-018-06156-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6168542PMC
October 2018

Rapid sample delivery for megahertz serial crystallography at X-ray FELs.

IUCrJ 2018 Sep 27;5(Pt 5):574-584. Epub 2018 Jul 27.

Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.

Liquid microjets are a common means of delivering protein crystals to the focus of X-ray free-electron lasers (FELs) for serial femtosecond crystallography measurements. The high X-ray intensity in the focus initiates an explosion of the microjet and sample. With the advent of X-ray FELs with megahertz rates, the typical velocities of these jets must be increased significantly in order to replenish the damaged material in time for the subsequent measurement with the next X-ray pulse. This work reports the results of a megahertz serial diffraction experiment at the FLASH FEL facility using 4.3 nm radiation. The operation of gas-dynamic nozzles that produce liquid microjets with velocities greater than 80 m s was demonstrated. Furthermore, this article provides optical images of X-ray-induced explosions together with Bragg diffraction from protein microcrystals exposed to trains of X-ray pulses repeating at rates of up to 4.5 MHz. The results indicate the feasibility for megahertz serial crystallography measurements with hard X-rays and give guidance for the design of such experiments.
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http://dx.doi.org/10.1107/S2052252518008369DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6126653PMC
September 2018

MHz frame rate hard X-ray phase-contrast imaging using synchrotron radiation.

Opt Express 2017 Jun;25(12):13857-13871

Third generation synchrotron light sources offer high photon flux, partial spatial coherence, and ~10 s pulse widths. These enable hard X-ray phase-contrast imaging (XPCI) with single-bunch temporal resolutions. In this work, we exploited the MHz repetition rates of synchrotron X-ray pulses combined with indirect X-ray detection to demonstrate the potential of XPCI with millions of frames per second multiple-frame recording. This allows for the visualization of aperiodic or stochastic transient processes which are impossible to be realized using single-shot or stroboscopic XPCI. We present observations of various phenomena, such as crack tip propagation in glass, shock wave propagation in water and explosion during electric arc ignition, which evolve in the order of km/s (µm/ns).
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http://dx.doi.org/10.1364/OE.25.013857DOI Listing
June 2017

Rapid Acquisition of X-Ray Scattering Data from Droplet-Encapsulated Protein Systems.

Chemphyschem 2017 May 10;18(10):1220-1223. Epub 2017 Apr 10.

Institute for X-ray Physics, Georg-August-University Göttingen, 37077, Göttingen, Germany.

Encapsulating reacting biological or chemical samples in microfluidic droplets has the great advantage over single-phase flows of providing separate reaction compartments. These compartments can be filled in a combinatoric way and prevent the sample from adsorbing to the channel walls. In recent years, small-angle X-ray scattering (SAXS) in combination with microfluidics has evolved as a nanoscale method of such systems. Here, we approach two major challenges associated with combining droplet microfluidics and SAXS. First, we present a simple, versatile, and reliable device, which is both suitable for stable droplet formation and compatible with in situ X-ray measurements. Second, we solve the problem of "diluting" the sample signal by the signal from the oil separating the emulsion droplets by multiple fast acquisitions per droplet and data thresholding. We show that using our method, even the weakly scattering protein vimentin provides high signal-to-noise ratio data.
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http://dx.doi.org/10.1002/cphc.201700221DOI Listing
May 2017

Following DNA Compaction During the Cell Cycle by X-ray Nanodiffraction.

ACS Nano 2016 12 24;10(12):10661-10670. Epub 2016 Nov 24.

Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany.

X-ray imaging of intact biological cells is emerging as a complementary method to visible light or electron microscopy. Owing to the high penetration depth and small wavelength of X-rays, it is possible to resolve subcellular structures at a resolution of a few nanometers. Here, we apply scanning X-ray nanodiffraction in combination with time-lapse bright-field microscopy to nuclei of 3T3 fibroblasts and thus relate the observed structures to specific phases in the cell division cycle. We scan the sample at a step size of 250 nm and analyze the individual diffraction patterns according to a generalized Porod's law. Thus, we obtain information on the aggregation state of the nuclear DNA at a real space resolution on the order of the step size and in parallel structural information on the order of few nanometers. We are able to distinguish nucleoli, heterochromatin, and euchromatin in the nuclei and follow the compaction and decompaction during the cell division cycle.
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http://dx.doi.org/10.1021/acsnano.6b05034DOI Listing
December 2016

X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells.

ACS Nano 2016 Mar 26;10(3):3553-61. Epub 2016 Feb 26.

Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.

In recent years, X-ray imaging of biological cells has emerged as a complementary alternative to fluorescence and electron microscopy. Different techniques were established and successfully applied to macromolecular assemblies and structures in cells. However, while the resolution is reaching the nanometer scale, the dose is increasing. It is essential to develop strategies to overcome or reduce radiation damage. Here we approach this intrinsic problem by combing two different X-ray techniques, namely ptychography and nanodiffraction, in one experiment and on the same sample. We acquire low dose ptychography overview images of whole cells at a resolution of 65 nm. We subsequently record high-resolution nanodiffraction data from regions of interest. By comparing images from the two modalities, we can exclude strong effects of radiation damage on the specimen. From the diffraction data we retrieve quantitative structural information from intracellular bundles of keratin intermediate filaments such as a filament radius of 5 nm, hexagonal geometric arrangement with an interfilament distance of 14 nm and bundle diameters on the order of 70 nm. Thus, we present an appealing combined approach to answer a broad range of questions in soft-matter physics, biophysics and biology.
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http://dx.doi.org/10.1021/acsnano.5b07871DOI Listing
March 2016

Modulation of frustration in folding by sequence permutation.

Proc Natl Acad Sci U S A 2014 Jul 7;111(29):10562-7. Epub 2014 Jul 7.

Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;

Folding of globular proteins can be envisioned as the contraction of a random coil unfolded state toward the native state on an energy surface rough with local minima trapping frustrated species. These substructures impede productive folding and can serve as nucleation sites for aggregation reactions. However, little is known about the relationship between frustration and its underlying sequence determinants. Chemotaxis response regulator Y (CheY), a 129-amino acid bacterial protein, has been shown previously to populate an off-pathway kinetic trap in the microsecond time range. The frustration has been ascribed to premature docking of the N- and C-terminal subdomains or, alternatively, to the formation of an unproductive local-in-sequence cluster of branched aliphatic side chains, isoleucine, leucine, and valine (ILV). The roles of the subdomains and ILV clusters in frustration were tested by altering the sequence connectivity using circular permutations. Surprisingly, the stability and buried surface area of the intermediate could be increased or decreased depending on the location of the termini. Comparison with the results of small-angle X-ray-scattering experiments and simulations points to the accelerated formation of a more compact, on-pathway species for the more stable intermediate. The effect of chain connectivity in modulating the structures and stabilities of the early kinetic traps in CheY is better understood in terms of the ILV cluster model. However, the subdomain model captures the requirement for an intact N-terminal domain to access the native conformation. Chain entropy and aliphatic-rich sequences play crucial roles in biasing the early events leading to frustration in the folding of CheY.
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http://dx.doi.org/10.1073/pnas.1324230111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4115504PMC
July 2014

Microsecond barrier-limited chain collapse observed by time-resolved FRET and SAXS.

J Mol Biol 2014 May 4;426(9):1980-94. Epub 2014 Mar 4.

Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA. Electronic address:

It is generally held that random-coil polypeptide chains undergo a barrier-less continuous collapse when the solvent conditions are changed to favor the fully folded native conformation. We test this hypothesis by probing intramolecular distance distributions during folding in one of the paradigms of folding reactions, that of cytochrome c. The Trp59-to-heme distance was probed by time-resolved Förster resonance energy transfer in the microsecond time range of refolding. Contrary to expectation, a state with a Trp59-heme distance close to that of the guanidinium hydrochloride (GdnHCl) denatured state is present after ~27 μs of folding. A concomitant decrease in the population of this state and an increase in the population of a compact high-FRET (Förster resonance energy transfer) state (efficiency>90%) show that the collapse is barrier limited. Small-angle X-ray scattering (SAXS) measurements over a similar time range show that the radius of gyration under native favoring conditions is comparable to that of the GdnHCl denatured unfolded state. An independent comprehensive global thermodynamic analysis reveals that marginally stable partially folded structures are also present in the nominally unfolded GdnHCl denatured state. These observations suggest that specifically collapsed intermediate structures with low stability in rapid equilibrium with the unfolded state may contribute to the apparent chain contraction observed in previous fluorescence studies using steady-state detection. In the absence of significant dynamic averaging of marginally stable partially folded states and with the use of probes sensitive to distance distributions, barrier-limited chain contraction is observed upon transfer of the GdnHCl denatured state ensemble to native-like conditions.
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http://dx.doi.org/10.1016/j.jmb.2014.02.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4010103PMC
May 2014

High-speed detector for time-resolved diffraction studies.

J Phys Conf Ser 2013 ;425(9)

Radiation Monitoring Devices, Inc., 44 Hunt Street, Watertown, MA 02472, USA.

There are a growing number of high brightness synchrotron sources that require high-frame-rate detectors to provide the time-scales required for performing time-resolved diffraction experiments. We report on the development of a very high frame rate CMOS X-ray detector for time-resolved muscle diffraction and time-resolved solution scattering experiments. The detector is based on a low-afterglow scintillator, provides a megapixel resolution with frame rates of up to 120,000 frames per second, an effective pixel size of 64 µm, and can be adapted for various X-ray energies. The paper describes the detector design and initial results of time-resolved diffraction experiments on a synchrotron beamline.
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http://dx.doi.org/10.1088/1742-6596/425/9/092005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905683PMC
January 2013

Sub-millisecond time-resolved SAXS using a continuous-flow mixer and X-ray microbeam.

J Synchrotron Radiat 2013 Nov 1;20(Pt 6):820-5. Epub 2013 Oct 1.

BioCAT, CSRRI and Department BCS, Illinois Institute of Technology, 3101 South Dearborn, Chicago, IL 60616, USA.

Small-angle X-ray scattering (SAXS) is a well established technique to probe the nanoscale structure and interactions in soft matter. It allows one to study the structure of native particles in near physiological environments and to analyze structural changes in response to variations in external conditions. The combination of microfluidics and SAXS provides a powerful tool to investigate dynamic processes on a molecular level with sub-millisecond time resolution. Reaction kinetics in the sub-millisecond time range has been achieved using continuous-flow mixers manufactured using micromachining techniques. The time resolution of these devices has previously been limited, in part, by the X-ray beam sizes delivered by typical SAXS beamlines. These limitations can be overcome using optics to focus X-rays to the micrometer size range providing that beam divergence and photon flux suitable for performing SAXS experiments can be maintained. Such micro-SAXS in combination with microfluidic devices would be an attractive probe for time-resolved studies. Here, the development of a high-duty-cycle scanning microsecond-time-resolution SAXS capability, built around the Kirkpatrick-Baez mirror-based microbeam system at the Biophysics Collaborative Access Team (BioCAT) beamline 18ID at the Advanced Photon Source, Argonne National Laboratory, is reported. A detailed description of the microbeam small-angle-scattering instrument, the turbulent flow mixer, as well as the data acquisition and control and analysis software is provided. Results are presented where this apparatus was used to study the folding of cytochrome c. Future prospects for this technique are discussed.
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http://dx.doi.org/10.1107/S0909049513021833DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3795536PMC
November 2013

Advances in turbulent mixing techniques to study microsecond protein folding reactions.

Biopolymers 2013 Nov;99(11):888-96

Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St., Worcester, MA, 01605.

Recent experimental and computational advances in the protein folding arena have shown that the readout of the one-dimensional sequence information into three-dimensional structure begins within the first few microseconds of folding. The initiation of refolding reactions has been achieved by several means, including temperature jumps, flash photolysis, pressure jumps, and rapid mixing methods. One of the most commonly used means of initiating refolding of chemically denatured proteins is by turbulent flow mixing with refolding dilution buffer, where greater than 99% mixing efficiency has been achieved within 10's of microseconds. Successful interfacing of turbulent flow mixers with complementary detection methods, including time-resolved Fluorescence Spectroscopy (trFL), Förster Resonance Energy Transfer, Circular Dichroism, Small-Angle X-ray Scattering, Hydrogen Exchange followed by Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy, Infrared Spectroscopy (IR), and Fourier Transform IR Spectroscopy, has made this technique very attractive for monitoring various aspects of structure formation during folding. Although continuous-flow (CF) mixing devices interfaced with trFL detection have a dead time of only 30 µs, burst phases have been detected in this time scale during folding of peptides and of large proteins (e.g., CheY and TIM barrels). Furthermore, a major limitation of the CF mixing technique has been the requirement of large quantities of sample. In this brief communication, we will discuss the recent flurry of activity in micromachining and microfluidics, guided by computational simulations, which are likely to lead to dramatic improvements in time resolution and sample consumption for CF mixers over the next few years.
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http://dx.doi.org/10.1002/bip.22355DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843316PMC
November 2013

Minireview: structural insights into early folding events using continuous-flow time-resolved small-angle X-ray scattering.

Biopolymers 2011 Aug 25;95(8):550-8. Epub 2011 Mar 25.

Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.

Small-angle X-ray scattering (SAXS) is a powerful method for obtaining quantitative structural information on the size and shape of proteins, and it is increasingly used in kinetic studies of folding and association reactions. In this minireview, we discuss recent developments in using SAXS to obtain structural information on the unfolded ensemble and early folding intermediates of proteins using continuous-flow mixing devices. Interfacing of these micromachined devices to SAXS beamlines has allowed access to the microsecond time regime. The experimental constraints in implementation of turbulence and laminar flow-based mixers with SAXS detection and a comparison of the two approaches are presented. Current improvements and future prospects of microsecond time-resolved SAXS and the synergy with ab initio structure prediction and molecular dynamics simulations are discussed.
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http://dx.doi.org/10.1002/bip.21628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278217PMC
August 2011