Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Chemistry & Biochemistry

First Advisor

Jennifer Kugel

Second Advisor

James Goodrich

Abstract

Transcription of mRNA is a very important and highly regulated processes necessary for the growth and viability of cells. Human p53 is a transcriptional activator that can act as a tumor suppressor by inducing cell cycle arrest and apoptosis. HMGB1 is an architectural protein that can bind and bend DNA to aid transcriptional regulation. This project investigated the potential for HMGB1 to facilitate DNA binding by p53. Various gel shift assays were performed to see if the addition of HMGB1 to reactions containing p53 and DNA would increase the amount of p53/DNA binding observed. On wild-type DNA containing two p53 response element half sites, the addition of HMGB1 did not result in an increase in binding. Similarly, on a shorter piece of DNA containing only one p53 response element half site, no additional p53 binding was observed in the presence of HMGB1. In a gel shift assay with DNA that was the same length as the wild type DNA but contained only one p53 response element half site, some facilitated binding of DNA by p53 was observed with HMGB1. In addition to looking at wild type tetrameric p53, two p53 mutants were created, one that forms only monomers, and one that forms only dimers. The monomeric mutant did not bind DNA. The dimeric p53 mutant bound DNA but at 10-fold the concentration at which wild type p53 bound. When HMGB1 was added to the dimeric mutant and DNA containing only one p53 response element half site, increased binding of a dimer to a single half site was observed. It is possible that HMGB1 increases specific binding of p53 to its consensus sequences. Further elucidation of the mechanism of p53 and HMGB1 binding DNA is important, as these complexes can play a key role in determining cell fate.

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