Navigation Links
A dual look at photosystem II using the world's most powerful X-ray laser
Date:2/14/2013

From providing living cells with energy, to nitrogen fixation, to the splitting of water molecules, the catalytic activities of metalloenzymes proteins that contain a metal ion are vital to life on Earth. A better understanding of the chemistry behind these catalytic activities could pave the way for exciting new technologies, most prominently artificial photosynthesis systems that would provide clean, green and renewable energy. Now, researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the SLAC National Accelerator Laboratory have taken a major step towards achieving this goal.

Using ultrafast, intensely bright pulses of X-rays from SLAC's Linac Coherent Light Source (LCLS), the world's most powerful X-ray laser, the researchers were able to simultaneously image at room temperature the atomic and electronic structures of photosystem II, a metalloenzyme critical to photosynthesis.

"This is the first time that femtosecond X-ray pulses have been used for the simultaneous collection of both X-ray diffraction (XRD) and X-ray emission spectroscopy (XES) at room temperature of a metalloenzyme crystal," says Junko Yano, a chemist with Berkeley Lab's Physical Biosciences Division who was one of the leaders of this research. "Collecting both diffraction and spectroscopy data from the same crystal under the same conditions is required for a detailed understanding of the mechanisms behind metalloenzyme catalysis."

Yano is a corresponding author, along with Vittal Yachandra, also a chemist with Berkeley Lab's Physical Biosciences Division, and Uwe Bergmann, a physicist with SLAC, of a paper about this research in the journal Science. The paper is titled "Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature." (See below for full list of co-authors.)

Photosystem II, a large protein complex in green plants, algae and cyanobacteria, is the only known biological system able to harness sunlight for the oxidation of water into molecular oxygen. Photooxidation of water by photosystem II is responsible for most of the oxygen in Earth's atmosphere. At the core of photosystem II is a manganese-calcium (Mn4Ca) complex that when energized by solar photons catalyzes a four photon-step cycle of oxidation states (S1-to-S4) that ultimately yield molecular oxygen. Scientists need to observe intact X-ray crystallography of the Mn4Ca ion in action but the molecule is highly sensitive to radiation.

"X-ray damage to metalloenzyme crystals has been a big issue for scientists even when the crystals were imaged at cryogenic temperatures," Yachandra says. "The LCLS is the world's only source of X-rays at this time capable of providing femtosecond pulses at the high intensities that enabled us to image intact photosystem II crystals before they were destroyed by exposure to the X-ray beams."

SLAC's LCLS is an X-ray free electron laser (XFEL) powered by a two-mile-long linear accelerator (or linac) that generates pulses of X-ray light on a femtosecond timescale. These pulses are more than a billion times brighter than those from the most powerful synchrotrons. SLAC is operated by Stanford University on behalf of DOE.

With their simultaneous XRD/XES experiments, Yano, Yachandra and their colleagues were able to observe the geometric structure and follow changes in the electronic structure of the Mn4Ca catalyst as they pumped the photosystem II crystal with visible-light laser pulses to simulate solar photons.

"We were able to unequivocally show that both the photosystem II complex and the Mn4Ca complex remain intact through the first two steps (S1 and S2) of the photooxidation process," says Yachandra.

Says Nicholas Sauter, Berkeley Lab computer scientist and a co-author of the study, "To be able to draw these conclusions, we've developed new software tools and are learning how to process the large amounts of data generated by studies such as this in real time."

For the next phase of this research, the researchers plan to study the final two steps in the photosystem II water-splitting process. Understanding how photosystem II is able to split water molecules into oxygen, electrons and hydrogen ions is crucial to the development of an effective and efficient artificial version of photosynthesis that could produce liquid fuels from nothing more than sunlight, carbon dioxide and water.

"Getting critical snapshots of the final photon steps in the photosystem II machinery would really answer all of the questions we have at the moment about how this system works," says Jan Kern, a chemist with Berkeley Lab's Physical Biosciences Division and SLAC who is the first author of the Science paper.

Says Yano, "We're interested in understanding the design principles in natural photosynthesis, which can only be obtained by collecting data from all the states and that will be useful for making artificial light-driven catalysts for water-splitting."

Beyond photosystem II and photosynthesis, the Berkeley Lab/SLAC team has demonstrated that simultaneous XRD and XES studies using ultra-short ultra-bright X-ray pulses can be used for future time-resolved studies of light-driven structural changes within protein and metal cofactors, and of chemical dynamics at the catalytic metal centers of metalloenzymes under functional conditions.

"We expect that this method will be applicable to many metalloenzymes, including those that are known to be very sensitive to X-ray photo-reduction and radiation damage, and over a wide range of time scales, starting with femtoseconds," Yano says.


'/>"/>

Contact: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
Source:Eurekalert  

Related biology news :

1. Nature Methods study: Using light to control cell clustering
2. Scientists using holiday snaps to identify whale sharks
3. Triple-negative breast cancer subtypes identified using microRNA
4. Just add water: How scientists are using silicon to produce hydrogen on demand
5. Using snail teeth to improve solar cells and batteries
6. MVI and Inovio partner to develop malaria vaccines using innovative vaccine delivery tech
7. USDA explores using novel genetic labs for faster detection of E. coli
8. Improving the development of new cancer models using an advanced biomedical imaging method
9. Got food allergies? Thanks to UCLA, you can test your meal on the spot using a cell phone
10. Using computational biology for the annotation of proteins
11. Detective work using terahertz radiation
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
A dual look at photosystem II using the world's most powerful X-ray laser
(Date:11/29/2016)... 29, 2016 Nearly one billion matches per second ... ... DERMALOG is Germany's ... efficient Identity Management. (PRNewsFoto/DERMALOG Identification Systems) ... DERMALOG is Germany's largest Multi-Biometric supplier: The company's Fingerprint Identification ...
(Date:11/21/2016)... Nov. 21, 2016   Neurotechnology , a ... technologies, today announced that the MegaMatcher On Card ... submitted for the NIST Minutiae Interoperability Exchange ... the mandatory steps of the evaluation protocol. ... continuing test of fingerprint templates used to establish ...
(Date:11/15/2016)... Nov. 15, 2016  Synthetic Biologics, Inc. (NYSE ... focused on the gut microbiome, today announced the ... shares of its common stock and warrants to ... a price to the public of $1.00 per ... Biologics from the offering, excluding the proceeds, if ...
Breaking Biology News(10 mins):
(Date:12/8/2016)... ... 08, 2016 , ... Opal Kelly, a leading producer of ... USB or PCI Express, announced the FOMD-ACV-A4, the company's first FPGA-on-Module for integration ... SODIMM-style module that fits a standard 204-pin SODIMM socket for low-cost integrations and ...
(Date:12/8/2016)... England , December 8, 2016 ... has expanded its customisable SureSeq™ NGS panel range with the ... allowing fast and cost-effective study of variants in familial hypercholesterolemia ... number variation (CNV) detection on a single small panel and ... hotspot content. This includes all exons for LDLR , ...
(Date:12/8/2016)... (PRWEB) , ... December 08, 2016 , ... ... data bioInformatics portal. In response to client demand KbioBox developed a sophisticated “3 ... biodesign program. Both are accessible from KBioBox’s new website, https://www.kbiobox.com/ ...
(Date:12/8/2016)... ... December 08, 2016 , ... ... World Technology Awards. uBiome is one of just six company finalists in the ... In addition to uBiome, companies nominated as finalists in this year’s awards include ...
Breaking Biology Technology: