Now, using intense X-rays from the Stanford Synchrotron Radiation Lightsource (SSRL) at the Department of Energy's SLAC National Accelerator Laboratory, researchers have determined the detailed structure of a key part of the ryanodine receptor, a protein associated with calcium-related disease.
Their results, which combine data from SSRL and the Canadian Light Source, pinpoint the locations of more than 50 mutations that cluster in disease "hotspots” along the receptor.
"Until now, no one could tell where these disease mutations were located or what they were doing,” said principal investigator Filip Van Petegem of the University of British Columbia in Vancouver.
The ryanodine receptor controls the release of calcium ions from a storehouse within skeletal-muscle and heart-muscle cells as needed to perform critical functions. Previous studies at lower resolution indicated that mutations cluster in three regions along the receptor, but without more detailed information it remained unclear exactly how they contributed to disease.
In a study published this week in Nature, Van Petegem and his group describe the structure of one of these hotspots in extremely fine detail and predict how the mutations might cause the receptor to malfunction and release calcium too soon.
The receptor is made up of more than 20,000 molecules called amino acids. Van Petegem's group studied a string of about 560 amino acids, where they found 57 mutations. In 56 cases, the mutations involved a change in a single amino acid, while the last one involved a deletion of 35 amino acids from the string.
"These mutations most likely cause the same disease effects, but a severe mutation leads to stronger symptoms, and doesn't require as big of a stimulus to induce disease,” Van Petegem said.
In the heart, the receptor is stimulated to open about once a second when the body is at rest, sending regular pulses of calcium into the rest of the cell. In skeletal muscles, the timing of the pulses is determined by how often the muscles contract. Each time the receptor opens, certain amino acids rearrange themselves to facilitate the calcium release. Mutations can disrupt this process by causing the receptor to open either earlier or more easily than it should.
This premature release of calcium produces extra electrical signals within the cells. In skeletal muscle, this can lead to fatal rises in body temperature under certain anesthetics, or the failure of major muscles. In cardiac muscle it can trigger an arrhythmia, resulting in sudden cardiac death. While it is difficult to determine the exact number of people with these mutations, it is estimated that as many as one in 10,000 may be at risk for disease.
"Thanks to the technological capabilities at SSRL, we were able to rapidly screen hundreds of crystallized samples of this receptor protein to find ones with the best quality, giving the best structure. This study is a good first step toward designing new molecules that could be used as a drug,” Van Petegem said. "These mutations could be a very promising therapeutic target for treating heart disease.”
Future studies at SSRL and other synchrotron facilities will map out other receptor hotspots where these disease mutations cluster and use the detailed information to better understand the complex functions of the protein.
"It is very exciting to see the significant impact of our advanced structural biology technologies in helping users address difficult projects,” said SSRL staff scientist Michael Soltis.
This research was supported by the Canadian Institutes of Health Research. The Stanford Synchrotron Radiation Lightsource is supported by the U. S. Department of Energy Office of Science. SLAC National Accelerator Laboratory is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science.
The Canadian Light Source is Canada's national center for synchrotron research. Located at the University of Saskatchewan in Saskatoon, the CLS is a powerful tool for academic and industrial research in a wide variety of areas including environmental science, natural resources and energy, health and life sciences, and information and communications technology. CLS operations are funded by the Government of Canada, Natural Science and Engineering Research Council, National Research Council of Canada, Canadian Institutes of Health Research, the Government of Saskatchewan and the University of Saskatchewan.
Melinda Lee | EurekAlert!
Unique brain 'fingerprint' can predict drug effectiveness
11.07.2018 | McGill University
Direct conversion of non-neuronal cells into nerve cells
03.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science