SAXS and MX data collected at SIBYLS enabled insights into protein flexibility in one of the proteins involved in Lou Gerigh’s disease. The results were recently published in PNAS and have been highlighted by Today At Berkeley Lab and and Daily Cal.
Protein framework alterations in heritable Cu, Zn superoxide dismutase (SOD) mutants cause misassembly and aggregation in cells affected by the motor neuron disease ALS. However, the mechanistic relationship between superoxide dismutase 1 (SOD1) mutations and human disease is controversial, with many hypotheses postulated for the propensity of specific SOD mutants to cause ALS. Here, we experimentally identify distinguishing attributes of ALS mutant SOD proteins that correlate with clinical severity by applying solution biophysical techniques to six ALS mutants at human SOD hotspot glycine 93. A small-angle X-ray scattering (SAXS) assay and other structural methods assessed aggregation propensity by defining the size and shape of fibrillar SOD aggregates after mild biochemical perturbations. Inductively coupled plasma MS quantified metal ion binding stoichiometry, and pulsed dipolar ESR spectroscopy evaluated the Cu2+ binding site and defined cross-dimer copper-copper distance distributions. Importantly, we find that copper deficiency in these mutants promotes aggregation in a manner strikingly consistent with their clinical severities. G93 mutants seem to properly incorporate metal ions under physiological conditions when assisted by the cop- per chaperone but release copper under destabilizing conditions more readily than the WT enzyme. Altered intradimer flexibility in ALS mutants may cause differential metal retention and promote distinct aggregation trends observed for mutant proteins in vitro and in ALS patients. Combined biophysical and structural results test and link copper retention to the framework destabilization hypothesis as a unifying general mechanism for both SOD aggregation and ALS disease progression, with implications for disease severity and therapeutic intervention strategies.
Pratt AJ, Shin DS, Merz GE, Rambo RP, Lancaster WA, Dyer KN, Borbat PP, Poole FL, Adams MW, Freed JH, Crane BR, Tainer JA, Getzoff ED. “Aggregation propensities of superoxide dismutase G93 hotspot mutants mirror ALS clinical phenotypes.” Proc. Natl. Acad. Sci. U.S.A. 2014 Oct 14 link
Recently in Science:
Structure determination of gold nanoparticles (AuNPs) is necessary for understanding their physical and chemical properties, but only one AuNP larger than 1 nanometer in diameter [a 102-gold atom NP (Au102NP)] has been solved to atomic resolution. Whereas the Au102NP structure was determined by x-ray crystallography, other large AuNPs have proved refractory to this approach. Here, we report the structure determination of a Au68NP at atomic resolution by aberration-corrected transmission electron microscopy, performed with the use of a minimal electron dose, an approach that should prove applicable to metal NPs in general. The structure of the Au68NP was supported by small-angle x-ray scattering and by comparison of observed infrared absorption spectra with calculations by density functional theory.
read about it here:
We are pleased to announce the 5th annual SIBYLS bioSAXS workshop “Frontiers in biological SAXS”
Date: October 7-8, 2014 Location: Advance Light Source (ALS) at Lawrence Berkeley National Laboratory , Berkeley, CA
Small angle scattering (SAS) is experiencing a dramatic increase in popularity within the structural biology community. The availability of synchrotron radiation, low-noise detectors, powerful computing hardware, and better algoritms, has made the technique accessible to a much larger audience than ever before. At the same time, biologists are investigating ever more complex systems that pose increasing challenges to conventional crystallography. The latest advances in SAXS studies on biological systems will be reported and discussed in 2 days workshop by invited experts with focus on following four topics (see program). 1) Advances in Synchrotron Scattering technique 2) Dynamic & Flexible Structures in Biomolecules 3) Membrane Protein Scattering 4) Complementary Methods in Crystals and in Solution
The two-day workshop will provide training on experimental techniques and software tutorial sessions primarily for biological SAXS studies. Participants will also receive updates on current development of software dedicated to analyze SAXS for structural biology. Half day of the workshop will be dedicated for data processing by workshop participants. Enrollment is limited to 30 participants.
Organizers: Michal Hammel, Greg Hura
Inquires: Jane Tanamachi
Registration: To attend “Frontiers in biological SAXS” you need register for the 2014 Advanced Light Source Users’ Meeting. ALS user meeting will be held at Berkeley Lab beginning Monday, October 6. “Frontiers in biological SAXS” will begin Thuesday October 7th and continue through Wednesday October 8th. When you registering, you must indicate “Frontiers in biological SAXS”
Tuesday, October 7th LBNL Building 2 , room 100B
11:30 Lunch at the ALS patio
12:30 Welcoming Remarks Michal Hammel and Greg Hura “Frontiers in biological SAXS”
12:45 Lois Pollack, Cornell Univesity
13:15 Edward Snell, Hauptman-Woodward Institute
13:45 Lokesh Gakhar, University of Iowa
14:15 Coffee Break
14:30 Greg Hura, LBNL
15:00 Dina Schneidman, University California, San Francisco “SAXS based modelling of proteins with long disordered fragments”
15:30 Sherry Wang, National Cheng Kung University, Taiwan “Molecular architecture and stepwise assembly of IL-33 signaling complex”
16:00 Michal Hammel LBNL “A molecular switch in nucleoid compaction dictates bacterial pathogenicity”
Wednesday, October 8th LBNL Building 2 , room 100B
9:00 Michal Hammel, LBNL “Data reduction and processing tutorial”
10:30 Coffee Break
10:45 Greg Hura “Data reduction and processing tutorial”
12:00 Lunch Break at the ALS patio
13:00 - till late Practical session with Mentors (Greg Hura, Michal Hammel, Dina Schneidman, Sherry Wang)
A new publication is available that describes practical aspects of collecting High-throughput SAXS data at the SIBYLS beamline, with a focus on challenging low concentration samples. Additional practical advice is laid out with respect to interpreting the resulting data.
Dyer KN, Hammel M, Rambo RP, Tsutakawa SE, Rodic I, Classen S, Tainer JA, Hura GL. “High-throughput SAXS for the characterization of biomolecules in solution: a practical approach.” Methods Mol. Biol. 2014;1091:245-58. link
The SIBYLS beamline was instrumental in providing key structural data for two recent publications exploring the dynamic nature of DNA repair.
The Mre11‐Rad50 complex is highly conserved, yet the mechanisms by which Rad50 ATP‐driven states regulate the sensing, processing and signaling of DNA double‐strand breaks are largely unknown. Here we design structure‐based mutations in Pyrococcus furiosus Rad50 to alter protein core plasticity and residues undergoing ATP‐driven movements within the catalytic domains. With this strategy we identify Rad50 separation‐of‐function mutants that either promote or destabilize the ATP‐bound state. Crystal structures, X‐ray scattering, biochemical assays, and functional analyses of mutant PfRad50 complexes show that the ATP‐induced ‘closed’ conformation promotes DNA end binding and end tethering, while hydrolysis‐induced opening is essential for DNA resection. Reducing the stability of the ATP‐bound state impairs DNA repair and Tel1 (ATM) checkpoint signaling in Schizosaccharomyces pombe, double‐strand break resection in Saccharomyces cerevisiae, and ATM activation by human Mre11‐Rad50‐Nbs1 in vitro, supporting the generality of the P. furiosus Rad50 structure‐based mutational analyses. These collective results suggest that ATP‐dependent Rad50 conformations switch the Mre11‐Rad50 complex between DNA tethering, ATM signaling, and 5′ strand resection, revealing molecular mechanisms regulating responses to DNA double‐strand breaks.
read more in the full articles…
Young researchers are encouraged to apply for the Cancun conference “Dynamic Structures in DNA Damage Responses and Cancer” from the 12-15th February, 2014. We expect that there will be lively discussions on both methods and results during the sessions and good opportunities to interact with top colleagues. To inspire your productive discussions the conference venue has breath taking views of the Caribbean Sea and a great beach to enjoy with colleagues. There are a few spots to join the conference and some for late breaking talks so if you or your group members would appreciate this intimate and informative meeting on dynamic structures in DNA damage responses and cancer, then we would encourage you to APPLY. We are putting together many of the people driving advances under one roof to make this a meeting that will prove uniquely productive and informative for those working in this area and seeking collaborators. Although you may have a busy schedule we aim to make this meeting worth your taking the time to participate by directly aiding research progress and collaborations.