Graduation Year

2010

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Biology (Cell Biology, Microbiology, Molecular Biology)

Major Professor

Lindsey Shaw, Ph.D.

Co-Major Professor

My Lien Dao, Ph.D.

Committee Member

Edward Turos, Ph.D.

Committee Member

Daniel Lim, Ph.D.

Keywords

MRSA, antibiotic resistance, fatty acid synthesis inhibitors, NsβL, β-lactams

Abstract

N-sec -butylthioloated β-lactam (NsβL) is a novel beta-lactam antimicrobial with a mechanism of action proposed to inhibit 3-oxoacyl-acyl carrier protein synthase (ACP) III (FabH), resulting in the inhibition of fatty acid synthesis. It has been suggested that NsβL inhibits FabH indirectly by inactivating coenzyme-A (CoA). CoA is an essential cofactor for numerous proteins involved in glycolysis, the citric acid cycle (TCA), and pyruvate metabolism, in addition to fatty acid biosynthesis. This study aimed to determine the effects of NsβL on a diverse array of laboratory and clinical Staphylococcus aureus isolates by analyzing the mode of resistance in spontaneous and adaptive mutant NsβL-resistant mutants. Phenotypic analysis of the mutants was performed, as well as sequence analysis of fabH; along with comparative proteomic analysis of intracellular proteomes. Our results indicate that NsβL resistance is mediated by drastic changes in the cell wall, oxidative stress response, virulence regulation, and those pathways associated with CoA. It is our conclusion that Nsβ

L has activity towards CoA, resulting in wide-spread effects on metabolism, virulence factor production, stress response, and antimicrobial resistance.

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