August 11, 2009

MX Frontiers at the One Micron Scale: Making the Case for Micro-Beams

Macromolecular crystallographic (MX) structure determination at synchrotron radiation sources has the potential to advance significantly through use of x-ray beams of one micron or smaller cross-sections. Recently, the MX Frontiers at the One Micron Scale workshop was held at Brookhaven National Laboratory to explore structural biology scientific opportunities made possible through the use of micro-beams. More than 100 attendees participated in the workshop, which included one-and-a-half days of lectures, discussions, and a semi-formal poster session.

On the first day of the workshop, speakers lectured about scientific opportunities, new crystallographic methods, radiation damage, and micro-focusing beamlines; while the second day was devoted to beamline concepts and challenges in optics and instrumentation. Posters were displayed throughout the workshop for viewing and discussion during coffee and lunch breaks.

Participants in the MX Frontiers workshop

On Thursday evening, a banquet was held at the Harbor Hills Country Club in Port Jefferson, where attendees enjoyed a buffet dinner overlooking the Sound and an after-dinner talk by microcrystallography pioneer Christian Riekel.

The following is a complete list of speakers and their corresponding lecture topics. Lecture abstracts and an increasing number of presentations are available via the workshop's website.

• Wayne Hendrickson, Life Sciences at NSLS-II
• David Eisenberg, Adventures in Microcrystallography of Biological Specimens
• Gebhard Schertler, The Structures of the G Protein Coupled Receptors
• John Spence, Femtosecond Crystallography of Protein Nanocrystals
• Irene Margiolaki, X-ray Powder Diffraction on Proteins
• Colin Nave, Radiation Damage, Minimising the Dose and Maximising the Signal
• Robert Fischetti, Microcrystallograpy and Mapping Radiation Damage with a 1-micron Beam at GM/CA-CAT
• James Holton, MLFSOM: Simulating the Diffraction Experiment on an Absolute Scale
• Elspeth Garman, Parameters Affecting Crystal Lifetime in MX and Possible Radiation Damage Mitigation Strategies
• Clemens Schulze-Briese, Protein Micro-crystallography at the Swiss Light Source
• Christian Riekel, Exploring Biological Matter with Micro- and Nanodiffraction
• Sean McSweeney, The Evolution of the ESRF's Structural Biology Beamlines
• Gwyndaf Evans, The I24 Microfocus MAD Beamline at Diamond Light Source
• Masaki Yamamoto, Protein Micro-Crystallography with a SPring-8 Micro-Beam Beamline
• Kenneth Evans-Lutterodt, Kinoform Focusing Optics for Macromolecular Crystallography
• Antonio Lanzirotti, Lessons Learned from K-B Mirror Based Microprobes

The workshop was particularly relevant given the development of NSLS-II, a brilliant new synchrotron facility under construction at BNL. As he welcomed participants on the first morning of the workshop, Laboratory Director Sam Aronson highlighted the essential role played by the crystallography community at the NSLS and expressed his hopes for their continued involvement in leveraging the expanded capabilities of NSLS-II.

Aptly, the workshop allowed speakers and participants to weigh in on how recent developments in crystallography may be used to inform the design of beamlines at NSLS-II. Workshop speakers and participants underscored the importance of incorporating full-automation and beamlines with the flexibility to deliver a stable one-micron beam as well as larger beams. Regarding the future at NSLS-II, Hendrickson predicted that "what we think of as difficult today will become routine by 2015."

Speakers in the MX Frontiers workshop

In addition to considering new ideas for NSLS-II, some shared current developments and future plans for other synchrotron facilities, including the Advanced Photon Source at Argonne National Laboratory, the European Synchrotron Radiation Facility, the Swiss Light Source, the Diamond Light Source, and the SPring-8 facility in Japan. By bringing together scientists from such widespread facilities, the workshop also provided a unique opportunity in scientific community building.

"To address issues that will come up in the next five to 10 years, we need to find better ways to integrate and share access to beamlines," said Sean McSweeney, emphasizing the value of cooperative development. Likewise, Gebhard Schertler indicated, "It is important how beamline scientists work with other scientists – they have to work on equal terms."

The workshop concluded with a final discussion that considered the key question of whether or not a solid case had been made in favor of micro-beams. Participants debated the matter with enthusiasm throughout, deliberating about the appropriateness of the one-micron scale, the role of submicrons, and the usefulness of beamlines with flexible capabilities.

Although as Colin Nave pointed out, "We're not yet in the position where all of the possibilities have been explored." Ultimately, the sum of lectures and discussions clearly illustrated that tiny beams will enable new science, particularly so if the beam is of sub-micron size. At this scale, structural work will be characterized by experimentation rather than routine measurements and involve many pursuits in life sciences such as MX, small-angle x-ray scattering, and fiber diffraction, potentially borrowing from electron microscopy as well. Finally, the workshop illuminated the benefits that micro-beams offer for the mitigation of radiation damage; however, more experimental verification and method development is needed.

The workshop was sponsored by the NSLS-II, NSLS, the U.S. Department of Energy's Office of Biological and Environmental Research and Office of Basic Energy Sciences, Brookhaven Science Associates, BNL's Biology Department, The National Institutes of Health's National Center for Research Resources, and the National Institute of General Medical Sciences. It was also supported commercially by FMB-Oxford Ltd, Bruker ASC, and Area Detector Systems Corporation, and organized by Dieter Schneider, Marc Allaire, and Lonny Berman (all of BNL).