title: Cell-Envelope Remodeling as a Determinant of Phenotypic Antibacterial Tolerance inMycobacterium tuberculosis.
abstract: The mechanisms that lead to phenotypic antibacterial tolerance in bacteria remain poorly understood. We investigate whether changes in NaCl concentration toward physiologically higher values affect antibacterial efficacy againstMycobacterium tuberculosis(Mtb), the causal agent of human tuberculosis. Indeed, multiclass phenotypic antibacterial tolerance is observed during Mtb growth in physiologic saline. This includes changes in sensitivity to ethionamide, ethambutol, d-cycloserine, several aminoglycosides, and quinolones. By employing organism-wide metabolomic and lipidomic approaches combined with phenotypic tests, we identified a time-dependent biphasic adaptive response after exposure of Mtb to physiological levels of NaCl. A first rapid, extensive, and reversible phase was associated with changes in core and amino acid metabolism. In a second phase, Mtb responded with a substantial remodelling of plasma membrane and outer lipid membrane composition. We demonstrate that phenotypic tolerance at physiological concentrations of NaCl is the result of changes in plasma and outer membrane lipid remodeling and not changes in core metabolism. Altogether, these results indicate that physiologic saline-induced antibacterial tolerance is kinetically coupled to cell envelope changes and demonstrate that metabolic changes and growth arrest are not the cause of phenotypic tolerance observed in Mtb exposed to physiologic concentrations of NaCl. Importantly, this work uncovers a role for bacterial cell envelope remodeling in antibacterial tolerance, alongside well-documented allterations in respiration, metabolism, and growth rate.
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, United Kingdom; Laboratory of Chemical Biology of Tuberculosis Pathogenesis, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Kensington, London SW7 2DD, United Kingdom.
authors.forename: Gérald
authors.initials: G
authors.lastname: Larrouy-Maumus
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, United Kingdom; School of Pharmaceutical Sciences, São Paulo State University (UNESP), 4801-902 Araraquara, SP, Brazil.
authors.forename: Leonardo B
authors.initials: LB
authors.lastname: Marino
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts 02115, United States.
authors.forename: Ashoka V R
authors.initials: AV
authors.lastname: Madduri
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute , Mill Hill Laboratory, London NW7 1AA, United Kingdom.
authors.forename: T J
authors.initials: TJ
authors.lastname: Ragan
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute , Mill Hill Laboratory, London NW7 1AA, United Kingdom.
authors.forename: Debbie M
authors.initials: DM
authors.lastname: Hunt
authors.affiliation: Laboratory of Chemical Biology of Tuberculosis Pathogenesis, MRC Centre for Molecular Bacteriology and Infection, Imperial College London , Kensington, London SW7 2DD, United Kingdom.
authors.forename: Lucrezia
authors.initials: L
authors.lastname: Bassano
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute , Mill Hill Laboratory, London NW7 1AA, United Kingdom.
authors.forename: Maximiliano G
authors.initials: MG
authors.lastname: Gutierrez
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts 02115, United States.
authors.forename: D Branch
authors.initials: DB
authors.lastname: Moody
authors.affiliation: School of Pharmaceutical Sciences, São Paulo State University (UNESP) , 4801-902 Araraquara, SP, Brazil.
authors.forename: Fernando R
authors.initials: FR
authors.lastname: Pavan
authors.affiliation: Mycobacterial Metabolism and Antibiotic Research Laboratory and Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute , Mill Hill Laboratory, London NW7 1AA, United Kingdom.
authors.forename: Luiz Pedro S
authors.initials: LP
authors.lastname: de Carvalho
keywords: Mycobacterium tuberculosis; cell envelope remodeling; lipids; osmolarity; phenotypic antibacterial tolerance