14th West Coast Protein Workshop

Summer 99

14th West Coast Protein Crystallography Workshop, Asilomar, CA, March 14-17,1999

Approximately 300 structural biologists attended this biannual workshop held at the Asilomar Conference Center in Pacific Grove. The workshop this year was organized by Tom Poulos (UC Irvine) and Ian Wilson (The Scripps Research Institute). 45 presentations by post-docs and graduate students were given in six sessions, and over 100 posters were the focus of discussions during the late evening social events. The weather was warm and the ocean provided its normal complement of sea otters. Most of the attendees were from California, but a few East Coast and international scientists also made it to the meeting. A complete list of the talks is available from the meeting website
www.scripps.edu/mb/wilson/asilomar/sched.html. Only a few of the talks presented are summarized here.


One of the sights available to meeting
attendeess between sessions

The Sunday night session contained seven talks describing crystallization and structural studies of membrane proteins and toxins. In this session, Richard Morse (UCSF),Borden Lacy (UC Berkeley), and Mark Knapp (Lawrence Livermore) described the structures of the Cry2Aa toxin, the Botulinum neurotoxin type A, and the tetanus toxin ganglioside binding domain. All three structures appear to use similar domains to bind their receptors. Monday morning, the presentations covered cell surface receptors and interactions. Zsuzsa Hamburger (Caltech) described the structure of a bacterial integrin-binding protein, invasin. One of the derivatives used to solve the structure was obtained using a Xenon pressure cell (200 psi) followed by rapid freezing to retain the Xe at reduced pressures. She stated that Xenon diffuses out of the crystals after 1 minute without freezing. A session on folding and design was also held Monday morning. Martin Sagermann (U. Oregon) showed the results of inserting repeated secondary structure elements into T4 lysozyme. Residues were inserted at one end of an alpha helix which resulted in an extended helix rather than a longer loop leading to the next secondary structure element. In another experiment, replication of a strand in the middle of a beta-sheet was accommodated by a shift of the following strands in the sheet and a formation of a long loop after the sheet was completed.
The Monday evening talks covered macromolecules capable of responding to signals of various sorts. One of the interesting talks in this session was given by Katya Zheleznova (Oregon Health Sciences Univ.) on BmrR, a transcription activator of a multidrug transporter. She showed how the protein contains an internal binding site capable of binding a large family of similar drugs. The ligands tend to be aromatic cationic compounds, and a buried glutamate residue is involved in their binding.

  The flavor of a workshop came with the Tuesday morning session on crystal growth, software, and synchrotron radiation. Paula Fitzgerald (Merck), chair of the first part of the session, started with an introduction pointing out the importance of choosing appropriate and memorable program names. One item of note in the crystallization talks was the statistical analysis of random crystallization screens carried out by Brent Segelke (Lawrence Livermore). His conclusion was that after 200-400 random crystallization screening experiments, you should investigate mutation of the protein or crystallization of the protein from another species. He was followed by Jacek Nowakowski (Scripps), who described a combinatorial crystallization screening system used to crystallize an RNA-DNA complex of a catalytic DNA molecule. Sequence variants of each of the nucleic acids were systematically combined and more than half of the molecules crystallized. Two of them showed diffraction spots beyond 3 Å resolution.
There were six talks Tuesday evening in a session on enzymes. David Schuller (UC Irvine) described the use of SIRAS methods and NCS averaging to solve the structure of heme oxygenase, the enzyme involved in the first step of heme catabolism. The structure is largely a-helical and has a tertiary structure not seen before. Ian MacRae (UC Davis) told of an interesting feature of the structure determination of APS kinase. Crystals of the protein grew well, but diffracted to only 2.9 Å resolution. Addition of polyethinimine resulted in slower growth and a different crystal form that diffracted to 1.9 Å. Protein-nucleic acid interactions were covered in the final session on Wednesday morning. Kevin Woods (UC Davis) showed the structure of a non-cleaving variant of the Cre recombinase in a DNA complex. The structure is trimeric although a tetramer had been anticipated based on the molecular biology of the system. Paul Foster (UCSF) described the structure of tRNA pseudouridine synthase I, a dimer solved at 1.5 Å resolution. Crystals of the enzyme were obtained by capillary dialysis through a gel plug (a technique described over 30 years ago).
Overall, the meeting continued the trend away from descriptions of experimental techniques and computational methods. As the presentations focus more on results and specific structures, it becomes harder to consider the meeting a workshop. Nonetheless, the informal nature of the meeting, the enthusiasm of the speakers, the quality of the science, and the setting continue to make the workshop successful. (Meeting organizers for 2001 are Bart de Vos (Genentech) and Rich Bott (Genecor International).
Ron Stenkamp
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