All ETDs from UAB

Advisory Committee Chair

Adrie Jc Steyn

Advisory Committee Members

William Benjamin

Kevin Dybvig

Michael Niederweis

Janet Yother

Document Type

Dissertation

Date of Award

2012

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, currently infects more than two billion people worldwide. Mtb is a highly adaptable pathogen, capable of modifying its metabolism in response to its environment. We previously showed that Mtb WhiB3 is a redox-responsive regulator of core intermediary metabolism and lipid anabolism through which it maintains redox homeostasis. In this work, through the use of metabolomic analysis and a novel radioactive thin layer chromatography assay, we discovered that WhiB3 regulates the production of the intracellular thiol ergothioneine (ergo) when using immunomodulatory lipid precursors as the major carbon source. Our results suggest that this regulation is mediated by an altered redox environment due to loss of WhiB3. We also found that loss of the major redox buffer mycothiol or the thioredoxin regulator SigH results in increased ergo levels, suggesting that ergo functions similarly to these redox stress protection mechanisms. Correspondingly, ergo-deficient Mtb mutants are more sensitive than wild-type to cumene hydroperoxide, an oxidative stressor. The fact that ergo levels are affected by the loss of WhiB3 implicates WhiB3 not only in redox maintenance but also in redox stress protection. Altogether, our results indicate that ergo can protect Mtb from redox stress and is differentially produced depending on the redox environment, such that factors regulating redox homeostasis indirectly regulate ergo biosynthesis. Our data provide a link between carbon metabolism and ergo production and suggest that the in vivo environment encountered by the bacilli determines ergo levels, thereby potentially predisposing Mtb to survive the many redox stresses it faces.

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