CAREER: The Relationship Between Transcription Termination and Replication in Saccharomyces cerevisiae

Troy University, Troy AL

Investigators

Abstract

MAGRATH The molecular processes that occur on a chromosome must either tolerate an overlap of factors and structures required for the independent molecular events or the processes must be separated. This research investigation will establish the relationship between two distinct molecular processes that require the utilization of genomic DNA as the primary molecular substrate - transcription termination by RNA polymerase II and DNA replication. Previous research has demonstrated that the sequences that mediate termination of transcription by RNA polymerase II are localized to the same genomic region as ARS (autonomous replication sequence) elements, and transcription directed into an ARS element can interfere with normal replicative activity. To extend these findings, the extent of protection from transcriptional interference that the transcriptional terminators that flank ARS elements provide will be established. Using the model eukaryote, Saccharomyces cerevisiae, the maximal level of transcriptional activity that can be directed into an ARS/terminator cassette, while still maintaining replicative efficiency, will be established. The creation of a battery of mutants will establish if an ARS/terminator cassette can be dissected into two independent activities. The level of transcription read-through from yeast genes located upstream of genomic ARS elements will be assessed, and the effect of disrupting normal transcription termination on replicative activity will be evaluated. In that all ARSs do not function as origins under all conditions, the level of transcription termination evident at various ARS sequences that are both replicatively functional and non-functional will be determined. Finally, to expand our studies to other diverse molecular processes, non-coding sequences within the yeast genome will be examined to determine the relative ability to terminate transcription and potentially reveal a more global role for transcription termination signals as molecular shields. In summary, this research investigates the potential overlap of different processes and determines if conflict among the different processes on the DNA exists. This project is ideal for inclusion into a molecular biology curriculum. While enriching students' education on the scientific process, this project will also give students a thorough and complete understanding of the molecular processes occurring on the chromosome.