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BIOCHEMICAL, STRUCTURAL, & COMPUTATIONAL STUDIES OF TREX1 EXONUCLEASE ACTIVITY

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title
BIOCHEMICAL, STRUCTURAL, & COMPUTATIONAL STUDIES OF TREX1 EXONUCLEASE ACTIVITY
author
Hemphill, Wayne O
abstract
The 3’ -> 5’ exonuclease TREX1 functions in vivo to degrade DNA and prevent stimulation of the DNA-sensing pathway cGAS-STING, which would otherwise instigate a spectrum of harsh autoimmune phenotypes. The prevailing model for TREX1 exonuclease activity in the literature purports it as a nonprocessive exonuclease with little in vitro preference for single-stranded versus double-stranded DNA substrates, and many studies assert sources of ssDNA as TREX1’s relevant biological substrate(s). In addition, TREX1’s obligate homodimeric structure, which is presumably relevant to its biological function, remains largely unjustified in the literature. Finally, TREX1’s gatekeeping role upstream of the cGAS-STING pathway, which is responsible for driving antitumor immunity in conventional anti-cancer therapies, identifies it as a promising immunotherapeutic target. Despite this, no potent TREX1 inhibitors existed in the literature prior to this work. In this dissertation, I critically re-evaluate the prevailing model of TREX1 exonuclease activity and develop the most promising small molecule TREX1 inhibitors reported using biochemical, structural, and computational studies. I find that TREX1 is in fact a semi-processive exonuclease with several orders of magnitude greater affinity for dsDNA than ssDNA, and consequently propose that TREX1’s relevant biological substrate is dsDNA. Furthermore, I elucidate inter-protomer coordination of activity as the function of TREX1’s dimeric structure and identify previously unstudied regions of the TREX1 enzyme as key contributors. Finally, I develop a number of potent and specific small molecule TREX1 inhibitors and characterize the underlying physicality of their activity.
subject
dsDNA
dynamics
inhibition
kinetics
mutations
TREX1
contributor
Perrino, Fred (committee chair)
Perrino, Fred (committee member)
Kridel, Steven (committee member)
Hollis, Thomas (committee member)
Grayson, Jason (committee member)
Lyles, Doug (committee member)
date
2021-06-03T08:35:51Z (accessioned)
2023-06-02T08:30:14Z (available)
2021 (issued)
degree
Biochemistry and Molecular Biology (discipline)
embargo
2023-06-02 (terms)
identifier
http://hdl.handle.net/10339/98780 (uri)
language
en (iso)
publisher
Wake Forest University
type
Dissertation

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