Structure And Function Of Transcription Elongation Factor Tfiis And Methanobacterium Thermoautotrophicum Protein 1615

Author : Valerie Booth
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

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Download or read book Structure and Function of Transcription Elongation Factor TFIIS and Methanobacterium Thermoautotrophicum Protein 1615 written by Valerie Booth and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: TFIIS is a general transcription elongation factor that helps arrested RNA polymerase II elongation complexes to resume transcription, through a mechanism that involves stimulating cleavage of the nascent RNA transcript. Previously, it was shown that yeast TFIIS is comprised of three structural domains I, II and III and the NMR solution structure of domain II was solved. I determined the structure of domain III and used it, with the structure of domain II, to interpret the results of an alanine scanning mutagenesis study. These studies identified several structural features responsible for different aspects of TFIIS function, including a basic patch of domain II, which is responsible for binding polymerase, and three surface aromatic residues, which appear to be positioned to bind nucleic acids via base stacking interactions. The structure-function studies indicated that the linker region between domains II and III might have an important role in constraining the spatial relationship between the domains. Therefore, NMR dynamics studies of TFIIS and an inactive mutant were undertaken to characterize their motional features. These indicated that the linker acts as a semi-rigid spacer between the two domains and the mutant exhibits a marked decrease in the correlation between the motion of the two domains. Small-angle X-ray scattering data was used to determine the distance between domains II, and III and suggested that a portion of the linker likely forms a compact structure, which may act like a spring in the interaction with the polymerase complex. This interaction was modeled using the recently determined structure of yeast polymerase. TFIIS domain I, as well as the homologous domains of elongin A and CRSP70, appear to have a more general role in transcription than the stimulation of elongation. In order to probe their function, I determined the NMR solution structure of this domain and used it to model the structures of the homologous proteins. This led to the identification of a conserved, basic patch on the surface of the domain I which is a likely location for an interaction common to all three proteins. The final target of my thesis was the structure of 'Methanobactetium thermoautotophicum' (MT) protein 1615. This protein was originally purified as part of a structural genomics project and was chosen as a target for structure determination due to its homology to the human protein, TFAR19, which is involved in apoptosis. The solution structure revealed a novel fold and the surface properties indicated MT1615 might be able to bind DNA, a hypothesis which was confirmed by gel electrophoretic mobility shift assay. The protein also contains a putative protein binding helix which suggests that MT1615 and TFAR19 could be transcription factors.