Search for the Structural Basis of Biomacromolecular Fun

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(1). We have completed the functional dynamics study of the L11-RNA-thiostrepton system, but decided not to pursue the structural determination of the ternary complex of L11-rRNA-thiostrepton as I have originally planed, because the result of our dynamics study appears to suggest that the structures of the ternary and the binary (L11-rRNA) complexes are similar. The results of the functional dynamics study has been written in a manuscript that was submitted to Journal of Molecular Biology. (2). We have nearly completed the "3P" (periodicity, Planarity and pixels) method development, and are in the process to program it in C++ in order to interface with the world-wide popular XPLOR-NIH package. The "3P" method was born out of a need to find a better way to determine structures like RAP that consists of periodical structural elements, and represents a significant departure from the traditional way of determining the structure using NMR data. One of the "3P" articles was selected for the cover page of Journal of Magnetic Resonance. A manuscript, the final installment of the "3P" project, has been written for a submission after the completion of the re-coding into C+++. This methodology development has facilitated our structural biology study of RAP, and will be useful for projects of structure determination in the future.The structural biology study of RAP and its interaction with the LRP receptor is an example of my vision as how a structural biology study should be conducted. This study tackled a difficult structural problem with a persistent effort, was aimed at the answering a fundamental biological question and was carried out with multiple collaborations. This project led to the discovery of a novel histidine switch that mediates the release of the LRP receptor in acidic environment in the Golgi, an important process involved in the receptor maturation. The mutants that we have made during the course of the study have potential therapeutic applications in treatment of diseases involved with the LRP receptor. We will apply for a US patent in the near future. The discovery of the histidine switch in RAP, a chaperone protein, trail blazes a new way to sequester the LRP receptor, and potentially other receptors, including LRP5 and LRP6 of the same family. Correct folding of LRP5/6 requires yet another specialized chaperone MESD. MESD can also be engineered to sequester LRP5/6 in the way similar to the mutated RAP to LRP, and this hypothesis sets a starting point to study the structural biology of the Wnt/beta-catenin signaling pathway. Looking into the future, to fulfill the research goal, I have setup several key collaborations with intramural and extramural groups. Among those, we plan to crystallize receptors or receptor fragments, whenever approiate, in collaboration with Dr. Ji's group; we plan to work with Dr. Shaprio's group to develop a new method for structure determination of large protein receptors and RNAmolecules; we plan to study the kinetic and thermodynamics in vitro of the interaction between the chaperones and the receptors in collaboration with Dr. Smith-Gill's group. We will continue our on-going collaboration with Professor Dudley Strickland group in the receptor biochemistry and biology.