NSF Award
0743298
This project will involve the analysis of transcript elongation by human RNA polymerase II (pol II) through precisely positioned single nucleosomes. This approach has already led to the identification of DNA sequences which impose exceptionally strong barriers to transcript elongation when assembled into nucleosomes. Use of this approach has also shown that contrary to initial expectations, removal of a single H2A/H2B dimer is not sufficient to allow pol II traversal for all nucleosomes. The current research project will continue to exploit the single-nucleosome system to achieve a greater understanding of the mechanism of nucleosome traversal by pol II. The experiments will address several important questions in this area. What is the relationship between the strength of the nucleosomal blockade to transcription and the affinity of DNA sequence elements within the nucleosome for the underlying histone proteins? What are the critical features of intermediates in the process of nucleosome traversal by pol II? To what extent does the core structure of the histone octamer affect the nucleosomal barrier? The N-terminal histone tails do not participate in the core structure of the nucleosome. What role do the tails play in controlling pol II traversal of the nucleosome? Transcript elongation factors for pol II which have been identified using pure DNA templates are at best partially effective in stimulating transcript elongation on nucleosomal templates. Will efficient pol II traversal of nucleosomes depend not only on factors which stimulate pol II but also on histone chaperones, which can transiently disrupt nucleosome structure during transcript elongation?<br/><br/>This research project also provides an excellent training opportunity for advanced undergraduate students. In addition to extending the classroom experience with cutting-edge technology, a summer spent in a research laboratory introduces students to the scientific method via practical examples. Undergraduates from local universities will participate in this research project during each summer of the support period.
