title: A metabolomics investigation of the function of the ESX-1 gene cluster in mycobacteria.
abstract: The ESX-1 gene cluster, encoding the Type-VII secretion (T7S) system and its virulence associated proteins, ESAT-6 and CFP-10, is thought to be responsible for the transport of extracellular proteins across the hydrophobic and highly impermeable, cell envelope of Mycobacterium, and is involved in virulence in Mycobacterium tuberculosis, the causative agent of tuberculosis. Using a GCxGC-TOFMS metabolomics approach, a M. smegmatis ESX-1 knock-out strain (ΔESX-1ms) was compared to that of the M. smegmatis wild-type parent strain, and the metabolite markers due to the presence or absence of the ESX-1 gene cluster were identified. A general increase in specific metabolites in the ΔESX-1ms, confirmed the roles previously described for ESX-1 in mycolic acid biosynthesis and cell wall integrity. However, a number of other metabolite markers identified indicates ESX-1 has an additional role the in cell envelope structure, altering the levels of antioxidants and energy metabolism. Furthermore, the metabolome profiles correlated with the metabolomic variation observed when comparing a hyper- and hypo-virulent Beijing strain of M. tuberculosis, suggesting that the pathways which modulate virulence in M. tuberculosis are also influenced by ESX-1, reaffirming the previously described association of ESX-1 with virulence and cell envelope biogenesis.
authors.affiliation: Human Metabolomics, North-West University, Potchefstroom, Private Bag x6001, Box 269, 2531, South Africa. Electronic address: dutoit.loots@nwu.ac.za.
authors.forename: Du Toit
authors.initials: DT
authors.lastname: Loots
authors.affiliation: Human Metabolomics, North-West University, Potchefstroom, Private Bag x6001, Box 269, 2531, South Africa.
authors.forename: Conrad C
authors.initials: CC
authors.lastname: Swanepoel
authors.affiliation: DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa.
authors.forename: Mae
authors.initials: M
authors.lastname: Newton-Foot
authors.affiliation: DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa.
authors.forename: Nicolaas C
authors.initials: NC
authors.lastname: Gey van Pittius
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001688:Biological Products / Q000032:analysis*; D055786:Gene Knockout Techniques; D055432:Metabolomics; D005810:Multigene Family; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001688:Biological Products; C093276:ESAT-6 protein, Mycobacterium tuberculosis
keywords: ESX-1; GCxGC-TOFMS; Metabolomics; Tuberculosis; Virulence