Deoxyribonucleotides as determinants of DNA replication fidelity in bacteriophage T4 Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/b8515s226

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Imbalanced deoxyribonucleoside triphosphate (dNTP) pools are mutagenic for DNA synthesis in both intact cells and cell-free replication systems. Almost certainly, such mutagenesis involves competition between correctly and incorrectly base-paired precursors at replication sites. However, there are certain differences between the intact cell and cell-free systems that do not always allow direct comparisons to be made with regards to mutagenesis stimulated by dNTP pool imbalances. For example, even though dNTP concentrations can be carefully controlled in vitro, cell-free replication systems almost certainly do not contain all of the components found at replication forks in vivo. In contrast, intracellular dNTP concentrations, and base changes in DNA, have not always been measured in parallel with conditions thought to cause imbalanced dNTP pools and mutagenesis in vivo. I describe in this dissertation the further development of a procaryotic system, namely bacteriophage T4, as a model in vivo system for studying dNTP pool imbalances and mutagenesis. While these investigations focus on two enzymes in T4 deoxyribonucleotide metabolism, namely T4 ribonucleotide reductase and dCMP deaminase, the effects of other phage mutations on dNTP pools and mutagenesis were also investigated. Loss of T4 dCMP deaminase activity during phage infections resulted in hyperexpanded hmdCTP pools, decreased dTTP pools, and expanded dGTP pools. There was a concomitant increase in AT-to-GC mutagenesis, which was confirmed by nucleic acid sequencing of amber⁺ phage revertants. To some degree, the aberrant dNTP pools and AT-to- GC mutation rates could be returned to normal by the addition of thymidine to infections by the dCMP deaminase deletion mutant, pseTΔ4, but not during infections by the dCMP deaminase missense mutant, cdN16. Both AT-to-GC and GC-to-AT mutations were weakly stimulated during T4 ribonucleotide reductase mutant, nrdBamB55, infections of ED8689/ pPS2, a host cell overproducing Escherichia coli (E. coli) ribonucleotide reductase. During T4 nrd⁺ infections, BrUdR mutagenesis preferentially stimulates GC-to-AT mutagenesis; while in uninfected E. coli, BrUdR stimulates the opposite pathway, namely AT-to-GC transitions. However, during nrdBamB55 infections of ED8689/pPS2, BrUdR mutagenesis now resembles that of uninfected E. coli, namely, AT-to-GC transitions prevail. I discuss a model based on these results that explains how BrUdR stimulates opposite mutagenic pathways in T4-infected and uninfected E. coli.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2013-07-02T21:21:54Z (GMT). No. of bitstreams: 1 SargentRoyGeoffrey1987.pdf: 1924479 bytes, checksum: 4f157af09d879c4e74c3553aa7a909c5 (MD5) Previous issue date: 1987-03-20
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-06-17T17:20:53Z (GMT) No. of bitstreams: 1 SargentRoyGeoffrey1987.pdf: 1924479 bytes, checksum: 4f157af09d879c4e74c3553aa7a909c5 (MD5)
  • description.provenance : Approved for entry into archive by Deborah Campbell(deborah.campbell@oregonstate.edu) on 2013-07-02T21:21:54Z (GMT) No. of bitstreams: 1 SargentRoyGeoffrey1987.pdf: 1924479 bytes, checksum: 4f157af09d879c4e74c3553aa7a909c5 (MD5)
  • description.provenance : Submitted by Kim Stowell (ksscannerosu@gmail.com) on 2013-06-13T22:31:19Z No. of bitstreams: 1 SargentRoyGeoffrey1987.pdf: 1924479 bytes, checksum: 4f157af09d879c4e74c3553aa7a909c5 (MD5)

Relationships

In Administrative Set:
Last modified: 08/22/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items