STRUCTURAL STUDIES OF MACROMOLECULES USING SYNCHROTRON RADIATION

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This proposal is concerned with the study of several different systems: a) type I DNA topoisomerases; b) chicken brain a-spectrin; c) domain I of the RNA component of RNase P, and d) several DNA binding proteins. The work is based on X-ray crystallography. We have been studying E. coli DNA topoisomerase I and III for a number of years and have proposed a catalytic mechanism. We are now in the process of studying the interactions of topoisomerase I with DNA and also the structure of mutant proteins that could shed light on the details of the reaction. We solved the structure of two repeats of chicken brain a-spectrin in 1997 using data collected at SSRL. We are now studying new crystals that contain three consecutive repeats. The third project is concerned with the structure of domain I of the RNA component of RNase P. This domain is 154 bases long and the crystals diffract to 3.3 ¿¿at a synchrotron source. The final project is concerned with the structure of ZntR, a metal-dependent transcriptional activator of E. coli. The crystals are small and we require synchrotron radiation for MAD phasing.