Meeting report

ACA 2013

Honolulu, Hawaii, July 2013
www.amercrystalassn.org/

[Hawaii logo]

Taken from ACA RefleXions, Fall, 2013

The meeting began with workshops on Biological SAXS - Theory & Practice; Getting the Most out of the Cambridge Structural Database, and on the GSAS-II Crystallographic Analysis System.

There were four Transactions symposia on various aspects of the Role in Crystallography of Neutron & Synchrotron Sources. TR.01, chaired by Richard Gillilan, was concerned with Small-Angle Scattering; TR.02, chaired by Christine Dunham, focused on Supramolecular Assemblies; TR.03, chaired by Antonio dos Santos and Jonathan Hanson, featured Emerging Characterization Facilities & Tools; and TR.04, chaired by Christine Beavers and Simon Teat, was about Chemical Crystallography.

Bau Award Lecture by Tom Koetzle

[Thomas Koetzle] Thomas Koetzle

The inaugural 2013 ACA Bau Award for Exceptional Research Achievement in Neutron Diffraction was presented to Thomas Koetzle. In his talk entitled 'From Amino Acid Structures to Metal Hydrides: Four Decades of Single-Crystal Neutron Diffraction', Tom reviewed highlights of the research carried out together with his collaborators at Brookhaven National Laboratory (BNL) and at Argonne's Intense Pulsed Neutron Source (IPNS).

Koetzle noted that less than 1% of reported crystal structures used neutrons. A new generation of neutron sources and instrumentation have removed some of the obstacles to such analysis. Nuclear positions are determined directly, thereby removing any bias that may be introduced in X-ray work due to asymmetries in the electron-density distribution. More important, hydrogen and deuterium are located with precision similar to carbon. The neutron's magnetic moment can also be exploited to examine spin densities, e.g. in molecular magnets.

At BNL in the '70s Koetzle worked with neutron diffraction pioneer Walter Hamilton studying precise structures of the amino acids. From these studies they were able to discuss the strength of the hydrogen bonds that play a central role in molecular recognition in biology.

The second theme of Tom's work at BNL was studies of transition metal hydride complexes that established the details of bonding of hydrogen to metals. This work was done in collaboration with Bob Bau and his research group at USC. This 25-year collaboration resulted in more than 40 publications. They utilized H/D substitutions to confirm the absolute stereochemistry of enzymatic reaction products, and their work established precise M-H distances in a variety of bonding environments for a variety of metals. Following the closure of BNL's high-flux beam reactor, Tom moved to Argonne's IPNS and continued his work there for a decade with Arthur Schultz and his group.

Koetzle concluded his lecture by reviewing the new sources coming on line and how they will impact the practice of neutron crystallography, making it possible to use smaller crystals and much shorter data collection times.

Fankuchen Award to Richard Dickerson (Lecture by Alexander McPherson)

[Alex McPherson] Alex McPherson

An overflow crowd attended a lecture by Alex McPherson honoring Richard Dickerson, recipient of the 2013 ACA Fankuchen Award. Dickerson sent a message expressing his appreciation to the ACA for the award.

McPherson treated us to a virtuoso lecture and placed Dickerson's many contributions to crystallography and structural biology in historical context. He showed vintage photographs of Sirs W. H. and W. L. Bragg, Lindo Patterson, David Harker, Linus Pauling, Dorothy Hodgkin, John Kendrew, Max Perutz, Francis Crick and Jim Watson. He reviewed milestones in the development of crystallization research, starting in 1840 with the crystallization of hemoglobin and leading up to the demonstration in the 1930's of diffraction from globular proteins by Bernal, Fankuchen and Hodgkin.

Dickerson was a graduate student in Bill Lipscomb's laboratory at Minnesota where he worked on boranes, receiving his PhD in 1957. He then worked with John Kendrew on the structure of myoglobin in England. He returned to the U. S. and at Caltech worked on the structure of cytochrome c. In 1969 Dick collaborated with the artist Irving Geis on 'The Structure and Action of Proteins'. This slim classic combined Geis's amazing illustrations with Dickerson's text and introduced generations of students to protein structure.

Alex concluded his lecture with a review of Dickerson's contributions to our knowledge of DNA structure. Dick's group was the first to obtain the atomic-resolution structure of B-DNA with the famous 'Dickerson dodecamer'. The Dickerson B-DNA model, together with Olga Kennard's model of A-DNA and Alex Rich's Z-DNA, undergirds much of today's explosive growth in nucleic acid structural research.

Dick Dickerson is a true giant in structural biology who was 'Present at the Flood', to quote the title of his 2005 book telling the story of how structural molecular biology came about.

Tom Koetzle

AW.03: Etter Early Career Award

[Eric Ortlund] Eric Ortlund

The 2013 Margaret C. Etter Early Career Award was presented to Eric Ortlund, Emory U, for elucidating structures of human nuclear receptors, pharmacological targets with high potential in a broad range of diseases. Eric described suppression of nuclear receptor signaling by a noncoding RNA. Noncoding RNAs are recognized as playing major roles in cell signaling and disease, yet the structural mechanisms driving their evolution and function are poorly defined. Eric's work is shedding much-needed light on this process.

Albert Reger

Kenneth Trueblood Award

[Tom Terwilliger] Tom Terwilliger

Tom Terwilliger received The Trueblood award for 'exceptional achievement in computational or chemical crystallography'. Terwilliger's lecture, 'Molecular replacement and model-building using distant homology models as templates', showed how to extend the reach of molecular replacement by using complementary information from the structure-modeling field and by using the local similarities of the search model to the structure to be determined. He presented a method he called 'morphing', in which a starting model is distorted (morphed) to improve its match to an electron-density map. He showed that a rather poor electron-density map can be used to morph a model with amazing accuracy, and to allow structures more distant from the target structure to be solved by molecular replacement.

Connie Rajnak

The 2014 meeting will be held May 24-28 in Albuquerque, NM. Details are available at www.amercrystalassn.org.