SAXS ON TRANSCRIPTION FACTOR IIF ASSOCIAT C-TERMINAL REPEAT DOMAIN PHOSPHATASE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Project 1 - Termination of transcription by RNA polymerase II is promoted by an interaction between the general transcription factor IIF (TFIIF) and the TFIIF-associating C-terminal repeat domain phosphatase (FCP1). The acidic C-terminal region of FCP1 is disordered in the free state, as indicated by NMR and CD spectroscopy, but adopts an ¿¿-helical conformation upon binding to the heavy chain of TFIIF. We have recently utilized 13C-detected NMR spectroscopy to generate comprehensive NMR chemical shifts of free ctFCP1 (residues 879-961) and secondary shift analysis of these data suggest that the equilibrium ensemble is biased towards ¿¿-helical conformation in residues 945-960 ¿¿" the TFIIF associating peptide ¿¿" despite the lack of persistent helical structure indicated by the CD results. We aim to gain further constraint on the overall hydrodynamic shape of the ctFCP1 solution ensemble through acquisition of SAXS data on the same 879-961 construct. Project 2 - We have recently solved the crystal structure of sheep liver sorbitol dehydrogenase (SORD). Earlier studies have confirmed that a hydrogen bonding network in mammalian SORD stabilizes a tetrameric state and is essential for the catalytic power. Our crystal structure does not support such a tetramer formation. We are interested in checking if the oligomer formed in solution matches with our crystal structure.