title: Dynamic exometabolome analysis reveals active metabolic pathways in non-replicating mycobacteria.
abstract: An organism's metabolic activity leaves an extracellular footprint and dynamic changes in this exometabolome inform about nutrient uptake, waste disposal and signalling activities. Using non-targeted mass spectrometry, we report exometabolome dynamics of hypoxia-induced, non-replicating mycobacteria that are thought to play a role in latent tuberculosis. Despite evidence of active metabolism, little is known about the mechanisms enabling obligate aerobic mycobacteria to cope with hypoxia, resulting in long-term survival and increased chemotherapeutic tolerance. The dynamics of 379 extracellular compounds of Mycobacterium smegmatis were deconvoluted with a genome-scale metabolic reaction-pair network to generate hypotheses about intracellular pathway usage. Time-resolved (13) C-tracing and mutant experiments then demonstrated a crucial, energy-generating role of asparagine utilization and non-generic usage of the glyoxylate shunt for hypoxic fitness. Experiments with M. bovis and M. tuberculosis revealed the general relevance of asparagine fermentation and a variable contribution of the glyoxylate shunt to non-replicative, hypoxic survival between the three species.
authors.affiliation: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.|PhD Program Systems Biology, Life Science Zurich Graduate School, Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Zimmermann
authors.affiliation: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.|PhD Program Systems Biology, Life Science Zurich Graduate School, Zurich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kuehne
authors.affiliation: Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Helena I
authors.initials: HI
authors.lastname: Boshoff
authors.affiliation: Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Clifton E
authors.initials: CE
authors.lastname: Barry
authors.affiliation: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Zamboni
authors.affiliation: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.
authors.forename: Uwe
authors.initials: U
authors.lastname: Sauer
mesh_terms: D001216:Asparagine / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology*; D006038:Glyoxylates / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D055442:Metabolome / Q000502:physiology; D020102:Mycobacterium smegmatis / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism
chemical_list: D006038:Glyoxylates; D001216:Asparagine; D010100:Oxygen