Mycolic Acids: From Chemistry to Biology

Daffé, Mamadou; Quémard, Annaık̈; Marrakchi, Hédia

doi:10.1007/978-3-319-50430-8_18

Cited by 19 publications

(23 citation statements)

References 176 publications

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“…However, the major contribution for the ecology and epidemiology of nontuberculous mycobacteria is the effectiveness of hydrophobic cell envelope, which acts as a permeability barrier, containing mycolic acids arranged predominantly in a direction perpendicular to the cell wall surface ( Nikaido et al, 1993 ; Hoffmann et al, 2008 ). Although the exact composition of the mycobacterial cell envelop is still being studied, most recent models propose an outermost layer, a cell wall and a conventional plasma membrane ( Daffé et al, 2017 ; Rodriguez-Rivera et al, 2017 ). The latter is mainly composed by phospholipids such as cardiolipin, phosphatidylethanolamine, phosphatidylinositol, and glycosylated phosphatidylinositols ( Crellin et al, 2013 ; Chiaradia et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Mycobacterial Response to Organic Solvents and Possible Implications on Cross-Resistance With Antimicrobial Agents

2018

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Mycobacterium vaccae, a bacterium found in soil, has been receiving attention as adjuvant to antituberculosis treatment, vaccines and immunotherapies and even as antidepressant. This bacterium is also able to degrade several pollutants, including aromatic compounds. The increasing presence of organic solvents in the environment may lead to M. vaccae adapted populations. A possible relationship between solvent tolerance and decreased susceptibility to other types of chemicals, including antibiotics, may pose a problem during opportunistic infections. The present study thus aimed at assessing if solvent adapted cells presented higher tolerance to antibiotics and efflux pump inhibitors (EPIs). M. vaccae cells were able to thrive and grow in the presence of up 20% (v/v) glycerol, 5% (v/v) ethanol, 1% (v/v) methyl tert-butyl ether (MTBE) and 0.1% (v/v) toluene. During adaptation to increasing concentration of ethanol and MTBE, the cells changed their fatty acid profile, zeta potential and morphology. Adapted cells acquired an improved tolerance toward the EPIs thioridazine and omeprazole, but became more susceptible to the antibiotics levofloxacin and teicoplanin when compared with non-adapted cells.

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Section: Discussionmentioning

confidence: 99%

Mycobacterial Response to Organic Solvents and Possible Implications on Cross-Resistance With Antimicrobial Agents

2018

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“…To confirm whether these MVs are released from the mycomembrane, we characterized their lipid contents using TLC (thin layer chromatography). The cell wall of Dietzia and related species such as Mycobacterium have a special mycomembrane consisting of mycolic acids [57]. We found trehalose dimycolate (TDM), trehalose monomycolate (TMM), and mycolic acids, which are the main components of the mycomembrane, in both MVs and the intact cells.…”

Section: Resultsmentioning

confidence: 93%

Extracellular heme recycling and sharing across species by novel mycomembrane vesicles of a Gram-positive bacterium

2020

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Microbes spontaneously release membrane vesicles (MVs), which play roles in nutrient acquisition and microbial interactions. Iron is indispensable for microbes, but is a difficult nutrient to acquire. However, whether MVs are also responsible for efficient iron uptake and therefore involved in microbial interaction remains to be elucidated. Here, we used a Gram-positive strain, Dietzia sp. DQ12-45-1b, to analyze the function of its MVs in heme-iron recycling and sharing between species. We determined the structure and constituent of MVs and showed that DQ12-45-1b releases MVs originating from the mycomembrane. When comparing proteomes of MVs between iron-limiting and iron-rich conditions, we found that under iron-limiting conditions, heme-binding proteins are enriched. Next, we proved that MVs participate in extracellular heme capture and transport, especially in heme recycling from environmental hemoproteins. Finally, we found that the heme carried in MVs is utilized by multiple species, and we further verified that membrane fusion efficiency and species evolutionary distance determine heme delivery. Together, our findings strongly suggest that MVs act as a newly identified pathway for heme recycling, and represent a public good shared between phylogenetically closely related species.

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“…No less than 60% of the mycobacterial cell envelope is estimated to be lipids as compared to 20% in the cell envelope of Gram-negative organisms (Brennan and Goren, 1979 ). Different models have been proposed for the mycobacterial cell envelope (Daffé and Draper, 1998 ; Marrakchi et al, 2014 ; Daffé et al, 2017 ). In one description, the cell envelope is schematically divided into three domains: (i) an outer layer or capsule which is primarily made up of proteins and lesser amounts of carbohydrates and lipids, (ii) a tripartite cell wall comprising an outer membrane (OM) that is covalently linked to an arabinogalactan-peptidoglycan complex, and (iii) an inner membrane (IM) (Daffé et al, 2017 ).…”

Section: The Mycobacterial Cell Envelopementioning

confidence: 99%

“… Schematic representation of the different components of the mycobacterial cell envelope based on the description given by Daffé et al ( 2017 ). Presentation is not drawn to scale.…”

Section: The Mycobacterial Cell Envelopementioning

confidence: 99%

The Mycobacterial Membrane: A Novel Target Space for Anti-tubercular Drugs

Chen

Nyantakyi

et al. 2018

Front. Microbiol.

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Tuberculosis (TB) poses an enduring threat to global health. Consistently ranked among the top 10 causes of death worldwide since 2000, TB has now exceeded HIV-AIDS in terms of deaths inflicted by a single infectious agent. In spite of recently declining TB incident rates, these decreases have been incremental and fall short of threshold levels required to end the global TB epidemic. As in other infectious diseases, the emergence of resistant organisms poses a major impediment to effective TB control. Resistance in mycobacteria may evolve from genetic mutations in target genes which are transmitted during cell multiplication from mother cells to their progeny. A more insidious form of resistance involves sub-populations of non-growing (“dormant”) mycobacterial persisters. Quiescent and genetically identical to their susceptible counterparts, persisters exhibit non-inheritable drug tolerance. Their prevalence account for the protracted treatment period that is required for the treatment of TB. In order to improve the efficacy of treatment against mycobacterial persisters and drug-resistant organisms, novel antitubercular agents are urgently required. Selective targeting of bacterial membranes has been proposed as a viable therapeutic strategy against infectious diseases. The underpinning rationale is that a functionally intact cell membrane is vital for both replicating and dormant bacteria. Perturbing the membrane would thus disrupt a multitude of embedded targets with lethal pleiotropic consequences, besides limiting the emergence of resistant strains. There is growing interest in exploring small molecules as selective disruptors of the mycobacterial membrane. In this review, we examined the recent literature on different chemotypes with membrane perturbing properties, the mechanisms by which they induce membrane disruption and their potential as anti-TB agents. Cationic amphiphilicity is a signature motif that is required of membrane targeting agents but adherence to this broad physical requirement does not necessarily translate to conformity in terms of biological outcomes. Nor does it ensure selective targeting of mycobacterial membranes. These are unresolved issues that require further investigation.

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Mycolic Acids: From Chemistry to Biology

Cited by 19 publications

References 176 publications

Mycobacterial Response to Organic Solvents and Possible Implications on Cross-Resistance With Antimicrobial Agents

Mycobacterial Response to Organic Solvents and Possible Implications on Cross-Resistance With Antimicrobial Agents

Extracellular heme recycling and sharing across species by novel mycomembrane vesicles of a Gram-positive bacterium

The Mycobacterial Membrane: A Novel Target Space for Anti-tubercular Drugs

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