Effect of the Spiroiminodihydantoin Lesion on DNA Base Pair Opening Dynamics, Nucleosome Assembly, and Base Excision Repair - PROJECT SUMMARY/ABSTRACT
Deoxyribonucleic acid (DNA) is the biological molecule within cells that is responsible for
transmitting and storing genetic information. Unfortunately, DNA can become damaged,
jeopardizing the integrity of this information that is vital for preserving health. Agents
that damage DNA, known as reactive oxygen species (ROS), are produced in the
normal course of cellular respiration as cells make energy by converting oxygen into
water. They can also be introduced by outside sources such as ionizing radiation and
certain transition metals. The experiments proposed here will focus on examining a
specific type of DNA damage called DNA base oxidation, where the structure of the DNA
base, responsible for storing genetic information, is altered. This particular type of DNA
damage has been implicated in causing cellular aging, cancer, and neurological
disorders like Alzheimer’s disease and amyotrophic lateral sclerosis.
The goal of this proposal is to investigate the effect of the spiroiminodihydantoin (Sp)
lesion on the dynamics, packaging, and repair of cellular DNA. This highly-mutagenic
lesion, which is formed when ROS react with guanine bases in DNA, produces the same
types of mutations found in some human lung tumors, and it has also been correlated
with the progression of color cancer in mice with infection-induced colitis. In order to
understand how cells detect and repair these kinds of DNA lesions, it is important to
examine their base pair opening dynamics. Nuclelar Magnetic Resonance (NMR)
techniques will be used in Specific Aim 1 to measure the base pair opening dynamcs for
the Sp lesion, allowing us to better understand how this lesion is located by DNA repair
proteins. The packaging of Sp lesions in nucleosomes, the most fundamental unit of
chromatin, will be examined in Specific Aim 2 with the goal of providing information
about how these lesions affect nucleosome assembly. Finally, in Specific Aim 3, the
ability of base excison repair proteins to excise the Sp lesion from nucleosomes will be
investigated. In sum, the results obtained from these studies will provide important
insight into the biological processing of the Sp lesion in cells and will allow us to better
understand how it may contribute to causing diseases like cancer.
