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Last Updated: | 29 AUGUST 2002 |
| Content Owner: | L. Dunn | |
| Page Editor: | L. Dunn |
**** **** **** * * * * * * **** **** **** * * * * * * **** **** * * **** HEADLINES - a digital monthly publication
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Contents of This Issue:
1. Science Highlight - ABC Transporter
Architecture and Mechanism
(contacts: Kaspar Locher, locher@caltech.edu,
Doug Rees, dcrees@caltech.edu)
Insights into the mechanisms of ABC transporters are emerging from macromolecular crystallography research by a Caltech research group led by Professor Douglas C. Rees. ABC transporters form a large family of membrane proteins that enable the translocation of a diverse range of substrates across cell membranes. Several human ABC transporters are medically relevant. For example, mutations in the cystic fibrosis transmembrane conductance regulator protein causes cystic fibrosis. A separate subclass of ABC transporters are associated with multidrug resistance in tumors. However, answers to critical questions about their translocation mechanisms have remained elusive.
The structure of a bacterial ABC transporter, the BtuCD protein, was recently solved from data collected at SSRL and APS. It is the first complete ABC transporter to have its high resolution (3.2 Å) structure determined in the physiological assembly, and it has yielded valuable insight into how ABC transporters work. In particular, three critical elements were visualized for the first time in an intact transporter: the substrate transport pathway, the power source for driving transport, and the "relay station" that transmits this power to the site of transport. While much remains to be learned about how substrate binds to the tranporter and what conformational changes are required for transport, the BtuCD structure provides a framework for addressing these central mechanistic issues.
More information regarding this research can be found on the SSRL home page and clicking on the picture under "Current Topics".
Of special note, the Rees group published another paper entitled "Structure of a Cofactor-Deficient Nitrogenase MoFe Protein" in the April 12, 2002 issue of Science (vol. 296 p. 352). This study, based in part on work done at BL7-1 at SSRL, has been dedicated to the memory of collaborator Barbara K. Burgess (January 1, 1951 to December 30, 2001). Barbara was an outstanding biochemist who greatly advanced the field of nitrogen fixation. She was also a long-time user of SSRL in collaboration with the Hedman-Hodgson research group and will long be remembered for her passion for science.
2. 3D X-ray Diffraction Microscope Provides
a First Deep View
(contact: Jianwei "John" Miao,
miao@slac.stanford.edu)
The successful effort of an international collaborative team from SSRL, SPring-8/RIKEN, APS and LBNL in the development of a high resolution 3D microscope by combining coherent x-ray diffraction with the oversampling phasing method earned the cover story of the August 19, 2002 issue of PRL. Using an undulator beam line at SPring-8, this microscope was used to image buried 2D and 3D nanostructures at 8 nm and 50 nm resolution, respectively. The imaging resolution is currently limited by the exposure time and the computing power, while the ultimate resolution is limited by the x-ray wavelengths. These results will pave the way for the development of atomic resolution 3D x-ray diffraction microscopy which can image thick materials not accessible to scanning probe microscopy and transmission electron microscopy. In combination with the planned x-ray free electron lasers, this form of microscopy could be applied to image single biomolecules at near atomic resolution. The team would like to acknowledge a number of people, most notably Piero Pianetta, Yoshinori Nishino, John Yang and Martin George for significant contributions that went a long way towards enabling the success of the experiment.
See J. Miao, T. Ishikawa, B. Johnson, E. H. Anderson, B. Lai and K. O. Hodgson, Phys. Rev. Lett. 89, 088303 (2002).
News articles include:
Related research was also highlighted by SSRL a year ago when the results of very promising simulations and computer modeling of imaging single biomolecules in 3-dimensions for the experiment were published in PNAS. See August 2001 Science Highlight
3. DOE Seeking to Improve and Streamline User
Access at Synchrotron Labs
(contact: Keith Hodgson,
hodgson@ssrl.slac.stanford.edu)
On August 2, officials of the U.S. Department of Energy's Office of Basic Energy Sciences (DOE BES) met with managers and directors from the four major DOE SR facilities to discuss issues concerning centralized management as well as general user information and access to beam lines. The meeting included BES officials Pat Dehmer, Iran Thomas, Bill Oosterhuis, Pedro Montano, and Bob Astheimer; SR facility representatives included Neville Smith, Gary Krebs (ALS); Dennis Mills, Roger Klaffky, Susan Strasser (APS); Steve Dierker, Chi-Chang Kao (NSLS); and Keith Hodgson, Cathy Knotts (SSRL).
Based in part on information from recent on-site program reviews and a DOE audit, DOE BES officials are urging that the synchrotron facitities revise their processes for reviewing and allocating user beam time, and reporting use and statistics to DOE. They would like the process to be as transparent as possible to the users and to have peer reviewed proposals as the primary means for determining access. Keith Hodgson and Neville Smith were asked to draft policies outlining the general principles agreed upon by each of the facilities and principles of user access. The afternoon session focused on the BES vision for user facilities over the next decade - a vision of facilities evolving more uniformly in order to facilitate access by general users as well as for review and reporting purposes. A key principle expressed was one of maximum openness to the research community at large.
4. 29th Annual SSRL Users' Meeting and 53rd
Meeting of the SSRL PRP
(contact: Cathy Knotts, knotts@ssrl.slac.stanford.edu)
The 29th Annual SSRL Users' Meeting and workshops will be held at SLAC on October 7-9, 2002. This meeting provides a forum for the presentation and discussion of research activities from SSRL users and the general synchrotron community. User research from SPEAR2 as well as discussions of new capabilities with SPEAR3 will be shared through invited talks and poster presentations. Users can register via the meeting website.
Four concurrent workshops covering a wide range of topics are being offered including:
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Workshop descriptions are posted to the Users' Meeting Workshops page and more detailed program information will be available from the same link soon.
The deadline for poster abstracts to be included in the printed program materials is September 23 (abstract form). Late posters will be accepted on a space available basis for the poster session. As has been the tradition, the poster session will include a graduate student poster competition. Prizes will be awarded at the Users' Meeting dinner, a high-spirited, Oktoberfest-themed event planned for October 7.
On Monday, August 26, the 53rd SSRL Proposal Review Panel Meeting was held. It was a productive and very successful meeting. The PRP reviewed 61 proposals and extension requests. Several presentations were made to the PRP, including ones on the LCLS project and SPPS experiment. The PRP expressed their interest, support, and willingness to work with SSRL on these and other future projects.
5. Nominations for the SSRLUO-EC Due
September 16th
(contact: Cathy Knotts, knotts@ssrl.slac.stanford.edu)
The SSRL Users' Organization Executive Committee (SSRLUO-EC) is currently seeking nominations for five general positions in the following disciplines: materials/chemistry (1); structural molecular biology (1), macromolecular crystallography (2), and (1) LCLS. In addition, nominations for a graduate student member of the committee (in any discipline) are needed. The SSRLUO-EC is a voluntary organization which serves as an advisory panel to communicate user needs or concerns to SSRL management and to the SLAC Scientific Policy Committee. More broadly, the SSRLUO-EC helps advocate the role synchrotrons play in the scientific enterprise. Members serve a two-year term, with the exception of the person elected Chair who serves a three-year term. Ballots will be distributed in late September, with the final voting held at SSRL's Annual Users' Meeting. All newly elected members begin their term immediately following the Users' Meeting. (see: http://www- ssrl.slac.stanford.edu/conferences/ssrl29/nominations.html)
6. Update on Beam Line Upgrades
(contact: Tom Rabedeau, rabedeau@ssrl.slac.stanford.edu)
In order to minimize the shutdown period for the installation and commissioning of SPEAR3 (April 2003-January 2004), much of the preparatory work has already been done or will be scheduled for completion in advance of the shutdown. Although most of this work is behind the scenes, there will be times when it impacts user operations on specific beam lines. Updated information of recent and upcoming beam line upgrade activities follows and is available at the SPEAR3 Update page.
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9. Upcoming Events at SSRL and Elsewhere
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8. User Research Administration Announcements
(contacts: Cathy Knotts, knotts@ssrl.slac.stanford.edu
Lisa Dunn, lisa@ssrl.slac.stanford.edu)
Our next user run begins November 11, 2002. User operation run dates are established after careful coordination between all the activities involved in delivering beam to users, including beam line development and construction projects, electrical, personnel protective systems, accelerator physics, maintenance and SPEAR3 preparations. Though a bit later this year, the November 11 start date reflects a comprehensive and aggressive schedule for all the work that has to be accomplished before the run can begin.
Beam Time Requests
As a reminder, the deadline for X-ray/VUV beam time requests for the
first scheduling period of the FY2003 SSRL experimental run, November 11,
2002 - January 27, 2003, is Friday, September 6, 2002. September 6 is also
the deadline for macromolecular crystallography beam time requests covering
the entire FY2003 run. Beam time requests can be submitted by fax at
650-926-3600 (for X-ray/VUV) or electronically for all beam lines via our
website:
A call for X-ray/VUV beam time requests for the second scheduling period
(January 28 - March 31, 2003) will be made in early November. The FY2003
SPEAR Operating Schedule which outlines shutdown periods and dates set
aside for maintenance and accelerator physics is available on our website
at:
http://www-
ssrl.slac.stanford.edu/schedules/Drft_2003_Run_Schd.pdf
As mentioned above, the FY2003 run is being scheduled in one large block for macromolecular crystallography beam lines. Several sets of shifts will be reserved on the schedule each month to accommodate Rapid Access applications approved for beam time throughout the run period. For more information on applying for Rapid Access beam time see: http://www- ssrl.slac.stanford.edu/users/user_admin/rapid_access.html
Call for User Surveys
Information collected on End-of-Run Summaries, which are required after
each experiment run at SSRL, is extremely important. This valuable data
helps us to understand what worked well (or not) for users. It is also a
mechanism for soliciting user suggestions for future improvements and
provides us with the information needed to complete statistical analysis
for annual reports to the DOE and other funding agencies.
If you have not yet completed an End-of-Run Summary for experiments conducted on SSRL beam lines during the FY2002 experimental run (November 2001 - July 2002), please take a few minutes and do so now by completing the electronic form.
We appreciate your input and thank you in advance for taking the time to
complete this survey.
SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical S ciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site: http://www-ssrl.slac.stanford.edu/
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