Award Date

8-1-2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Committee Member

Eduardo A. Robleto

Second Committee Member

Brian P. Hedlund

Third Committee Member

Helen J. Wing

Fourth Committee Member

Ernesto Abel-Santos

Number of Pages

59

Abstract

Since the 1950’s it has been shown that bacterial cells accumulate mutations even in non- dividing conditions, but how this type of mutation occurs is still highly debated. In Bacillus subtilis, Mfd, a precursor of the nucleotide excision repair (NER) system, mediates the formation of mutations in stationary-phase or non-replicating cells. In growing cells, Mfd recruits repair when RNA polymerase is stalled during transcription; it then recruits proteins from NER to repair damage. Here, we examine the hypothesis that Mfd mediates the formation of mutations by interacting with cellular components that repair reactive oxygen species (ROS), a natural byproduct of bacteria cell respiration. Utilizing two oxidants, we tested the hypothesis that Mfd protects cell viability and mutation development after exposure to ROS in stationary-phase. Our data showed that Mfd mitigated damage caused by reactive oxygen species and that such effect is independent of the NER system. Also, Mfd, MutY and reactive oxygen species mediated the formation of mutations in stationary-phase cells.

Keywords

Bacillus subtilis; Mfd; Oxidative damage repair; Stationary-phase mutagenesis; Transcription

Disciplines

Biology | Genetics | Microbiology

Language

English


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