Finding novel strategies to kill TB: The response of Mycobacterium tuberculosis to carbon source shifts
Competition funded project (student worldwide). Self-funded students only
Despite decades of research on Mycobacterium tuberculosis many aspects of the basic biology of this important pathogen remain unclear. We are using physiology driven systems biology to dissect the metabolic strategy of M. tuberculosis within the host macrophage with the overarching aim of identifying novel druggable targets. We have developed systems biology tools for interrogating the metabolism of M. tuberculosis on a genome scale and measuring the metabolic fluxes of M. tuberculosis growing both in vitro and also within host cells. Recently we have developed expertise in single cell microfluidics which allows us to explore mycobacteria at the single cell level. The goal of this research project is to apply these powerful tools to study how M. tuberculosis responds to carbon source switches. This is of therapeutic significance as deregulating intracellular metabolism offers an attractive alternative to conventional antimicrobial chemotherapy.
Bacteria must be able to adapt rapidly to unpredictable alterations in their environment. This is particularly critical for the survival of intracellular pathogens such as M. tuberculosis which have the challenge of acquiring nutrients while being surrounded by a membrane derived from another organism, and the environment encountered by these bacteria is unusually dependent on the physiology of the host. Evidence suggests that immune induced alterations in the mycobacterial phagosome alter the availability of carbon sources. Adapting to carbon source shifts is therefore critical to the survival of M. tuberculosis. Additionally intracellular pathogens sense different metabolic environments as indicators of their location in the host and modify their response to optimise survival.
Increasing evidence suggests that M. tuberculosis exists on a mixed diet in its human host macrophage cell which includes cholesterol, fatty acids and amino acids. However nutrient availability will also change during the course of TB disease as in addition to replicating within the phagosome of macrophages M. tuberculosis can also escape the phagosome and survive within the cytoplasm, survive within other cell types and also complex immunological structures called granulomas. M. tuberculosis must therefore be able to successfully switch from one nutrient state to another. Elegant studies in Escherichia coli using flow cytometry and single cell microfluidics have shown that shifts in nutrient sources unexpectedly generated sub populations of bacteria. This project aims to apply the same techniques to M. tuberculosis to test the hypothesis that carbon source switching generates metabolic subpopulations.
To explore the physiological and molecular mechanisms involved when M. tuberculosis adapts to shifts in carbon sources.
The student will receive training in mycobacteriology, molecular biology, microfluidics and eukaryotic cell culture and working at containment level 3. Fluorescent reporter strains will also be used to monitor the expression of key metabolic enzymes in response to shifts in carbon sources.
Impact and significance
These studies will unravel how M. tuberculosis adapts to changing carbon sources including those relevant to the host environment.
Fundamental basic research such as this is a critical first step in the development of new TB therapeutics.
Applicants are expected to hold a good honours degree (upper second) in an appropriate discipline, but prior experience in research or industry may be acceptable. Enthusiasm for, and commitment to, independent study is essential.