Replication of g-quadruplex DNA by translesion polymerases

The National Science Foundation (NSF) awarded a $1,100,000 Project Grant (CFDA 47.074 - Biological Sciences) to the University of Arkansas for Medical Sciences (UAMS) to study the replication of G-quadruplex DNA by translesion polymerases. This project aims to determine how proteins are recruited to sites of DNA replication and function together to copy G-quadruplex DNA structures, which can act as barriers to accurate genome replication. The research will elucidate the molecular mechanisms underlying the evolutionary selection of the REV1 translesion synthesis enzyme for promoting the successful resolution of G-quadruplex motifs. The project will also support the scientific training of high school, undergraduate, and graduate students, with a focus on broadening participation from underrepresented groups in the sciences. Additionally, UAMS has provided a $234,125 sub-grant to Hendrix College to contribute to this research on G-quadruplex DNA replication.

Abstract

All lifeforms depend on accurate replication and maintenance of their genome for growth, adaptation, and survival. Certain nucleic acid sequences rich in guanine can fold into four-stranded quadruplexes (G4) that present a natural barrier to DNA replication. These nucleic acid structures help control diverse cellular functions that drive evolution and affect the overall physiology and health of organisms. Additionally, G4 motifs play critical roles in human disease. For example, alterations in G4 regulatory processes contribute to neurological conditions, such as alzheimer?s disease, parkinson?s disease, amyotrophic lateral sclerosis/frontal-temporal dementia, and fragile x syndrome. Dysregulation of G4 biology also impacts cancer in multiple ways, such as through activation of genes that promote tumor growth and survival. Even the natural process of aging is thought to depend to some degree on how reactive chemical species alter G4 motifs. The goal of this project is to determine how specific proteins are recruited to sites of replication and then function together to copy G4 DNA. The project will support scientific training of high school, undergraduate, and graduate students. Many of the trainees will come from groups that are underrepresented in the sciences and from schools with limited resources. Inclusion of these students will broaden participation and enhance career trajectories while also improving scientific literacy in communities that otherwise might not have exposure to scientific research. In this regard, the project will produce two main outcomes: (1) IT will increase knowledge of molecular mechanisms that have evolved to maintain functionally important genomic regions across the tree of life and (2) IT will help promote student performance and retention in biochemistry, molecular biology, and biomedical science programs. Plasticity in response to impaired fork progression is critical for bypass and tolerance of a variety of agents that challenge timely and accurate DNA replication. Translesion DNA synthesis (TLS) is an ancient mediator of the replication stress response. This project will elucidate the molecular and cellular features of REV1 that led to the evolutionary selection of this TLS enzyme as a principle means of promoting successful resolution of G4 motifs. Both in vitro biochemical and biophysical techniques will be combined with cellular approaches to advance models describing the mechanics of REV1-mediated G4 bypass and the importance of interactions with other replication proteins. The summation of the work will provide new insights that will advance models describing replication of difficult-to-replicate sequences that are conserved across species. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are planned for this award.