The Interaction Between Telomerase and the Chromosome

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

Michael Jarstfer Proposal: 0446019 Telomerase is a remarkable nucleic acid polymerase that uses a portion of its integral RNA subunit as a template for the synthesis of the 3' strand of DNA found at both ends of linear eukaryote chromosomes. The product of telomerase activity is a single strand of repetitive G-rich DNA that is part of a specialized nucleoprotein complex called the telomere. The telomere functions by preventing degradation and untoward recognition of the chromosome ends by the normal DNA repair machinery. When telomerase activity is suppressed, telomeric DNA is not maintained and each complete cell cycle results in increasingly shorter telomeres. This telomere erosion is thought to function as a biological clock that determines the extent of cellular proliferation. If cells continue to divide in the absence of telomere maintenance, genetic instability and cell death ensues. The role of telomeres in regulating cellular proliferation suggests that understanding the mechanism of telomerase will have broad implications. To further the understanding of telomerase, this project will examine the salient features of the interactions between telomerase and the chromosome using a multifaceted approach. The first objective of this project is to examine the interaction between telomerase and synthetic chromosome models. Techniques including electron microscopy, enzyme kinetics, and DNA footprinting will be used to determine the global features of the telomerase-telomere interaction. The second objective is to examine the interaction between telomerase and a specialized structure of DNA called a G-quadruplex. Because the G-rich DNA of the telomere can fold into G-quadruplex structures, it is necessary to characterize the G-quadruplex-telomerase interaction to fully comprehend the behavior of telomerase at the chromosome end. The final objective is to characterize specific interactions at the individual nucleotide level between the template of telomerase, which is contained in the middle of its RNA subunit, and the telomeric DNA primer. Completing this objective will provide a working model for primer alignment and extension during the telomerase reaction cycle. The successful completion of this project will provide a comprehensive view of the interaction between telomerase and the telomere and allow a more complete comparison between the catalytic capabilities of telomerase and other nucleic acid polymerases. The project also involves the training of undergraduate and graduate students in the laboratory, as well as participation in a summer program for undergraduate minorities.