SAXS STUDY OF NUCLEOTIDE-DEPENDENT CONFORMATIONAL CHANGE IN AB-TUBULIN AND HSP90

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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. Ab-tubulin and the molecular chaperone HSP90 have essential non-overlapping roles in the life of eukaryotic cells. Both proteins bind and hydrolyze nucleotide triphosphates (GTP for tubulin, ATP for HSP90), and are known to adopt multiple conformations, as part of their functional cycle. It is not known, however, whether these conformational changes arise directly as a function of nucleotide state, or instead as a result of protein:protein interactions (self-assembly into microtubules for Ab-tubulin, substrate/co-chaperone binding in the case of HSP90). Studying how the conformations these of two different proteins respond to nucleotide state will be an essential first step in formulating a meaningful mechanistic understanding of their function. We propose to use small-angle X-ray scattering (SAXS) to measure scattering profiles as a function of nucleotide state, and thereby obtain vital structural insight into any potential changes in the conformational preferences of these proteins.