From Director Chi-Chang Kao:
Structural Molecular Biology at SSRL
 The goal of understanding biological structure and function, and applying this knowledge to address a wide range of issues with broad societal importance, has evolved into a large multidisciplinary effort. It engages researchers whose goals range from innovative, discovery-based science through applied uses like the acceleration of drug discovery. Knowledge in this field has relevance to solving grand challenge problems related to medicine, energy, and the environment. Within this context, the SSRL Structural Molecular Biology (SMB) program is focused on obtaining and utilizing biomolecular structural information on the nano-to-atomic scale to understand function (and malfunction) of biological processes relevant to human health, sustainable energy, and other areas. The SMB program will continue to develop and provide state-of-the-art facilities and methodologies to study the most challenging biological macromolecular systems, using a combination of macromolecular x-ray crystallography, biological small angle x-ray scattering/diffraction, x-ray imaging, and x-ray absorption spectroscopy.
Macromolecular crystallography will focus on structural studies of increasingly large and challenging macromolecular assemblies, crucial to advancing the understanding of complex biochemical processes. A second focus will be on membrane proteins, which are of major pharmacological importance, but exceptionally challenging to crystallize. A third area will be on controlling radiation damage to enable structure determination of specific chemical states of metalloproteins to understand enzymatic processes related to disease and bioenergetics. Emphasis will be given to the following developments:
- Novel crystallography data collection strategies for weakly diffracting samples, capitalizing on enhanced characteristics of novel detectors
- Micro-beam capabilities to study micro-crystals or inhomogeneous larger crystals
- Sample handling techniques for room temperature and high throughput studies of chemically and mechanically sensitive samples
- Integrated non-synchrotron radiation spectroscopies for in-situ monitoring of electronic states in metalloproteins
- Fully automated multi-crystal data collection pipelines to 1) preserve the oxidation state in metalloprotein active sites, 2) mitigate radiation damage in weakly diffracting and/or microcrystal systems, and 3) accelerate fragment-based drug discovery in collaboration with Biopharma
- High-throughput structure determination tools together with the Joint Center for Structural Genomics
Biological small-angle x-ray scattering and diffraction (BioSAXS), which enables structure determination at lower resolution but under non-crystalline, near physiological conditions—in solution or as partially ordered biomolecular arrays—will focus on very large protein assemblies, viruses, protein families related to the human microbiome, and drug delivery systems. The studies will extend into shorter time-domains (sub-millisec) and be enabled by increased automation. Emphasis will be given to the following developments:
- Advanced automation with minimized sample volume and reduced measurement time, coupled with computational approaches to automate data quality assessment and data analysis, to create a fully automated pipeline
- Enhancement of time-resolved SAXS capabilities to the sub-millisecond time regime and exploring new reaction triggering schemes
- Development of microfluidic approaches to high throughput solution scattering and time-resolved solution scattering experiments
Biological x-ray absorption spectroscopy (BioXAS), which provides exquisite local structural knowledge (electronic and geometric) about the active sites in metalloproteins, will address structure-function relationships for enzymatic systems related to cancers, neurological systems, metabolic disorders, and metal deficiencies, among others. The biological systems will be studied over a range of energy, size, and time-scales, with separate but complementary techniques, and with particular emphasis on understanding biological reaction intermediates. Developments will focus on:
- Enhancement of dilute solution, and polarized protein crystal, XAS capabilities coupled with approaches to generate and study reaction intermediates, including with in-situ non-synchrotron radiation spectroscopies
- Advanced high-resolution and site-selective XAS and XES, and extension of these methods to the micro-second time domain through energy dispersive XES, coupled to developments at SLAC's Linac Coherent Light Source for more rapid enzyme kinetics
- Soft x-ray spectroscopy (2-5 keV) for microXAS imaging and solution studies for cellular imaging of low Z atoms and their relation to development, ageing, and disease
- Hard x-ray microXAS imaging with chemical speciation enabled by edge and EXAFS, on length scales from micron to mm, for biomedical and biological cell-to-tissue specimen
New Frontiers
The Linac Coherent Light Source (LCLS) is showing great promise for determining macromolecular structures from nano-sized crystals and possibly mitigating radiation damage altogether (diffraction before destruction). The LCLS also opens a new window in the time domain that is more than 103 faster than currently accessible using synchrotrons for the study of biomolecular processes, opening access to a new regime of structural biodynamics and biochemical reactions. The SSRL SMB scientists are well positioned to work closely with LCLS to help drive "in-house" developments, through engagement in methodology and structural biology scientific projects, for the benefit of the scientific community.
Finally, we will educate and train the next generation structural biology scientists through tailored workshops, summer schools, web-based tools, mentoring of students and postdoctoral fellows, and by bringing the synchrotron to the home laboratory through advanced remote-access developments in tandem with rapid access beam time systems.
This article originally appeared in the March 2012 edition of
SSRL Headline News.
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Questions? Please contact Lisa Dunn
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