Porins in the Cell Wall of Mycobacteria

Trias, Joaquim; Jarlier, Vincent; Benz, Roland

doi:10.1126/science.1279810

Cited by 204 publications

(159 citation statements)

References 13 publications

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“…Gram-positive bacteria were long supposed to lack porin channels. However, porin-like channels have been recently identified in the cell wall of Gram-positive bacteria such as Mycobacterium chelonae (5,6), Mycobacterium smegmatis (7), and Corynebacterium glutamicum (22). These bacteria are known to contain lipids in their cell wall in the form of mycolic acids, and it is possible that mycolic acids and other lipids form part of another bilayer (23), explaining the low permeability of the mycobacterial cell wall (24).…”

Section: Resultsmentioning

confidence: 99%

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Besnard

Martinac

Ghazi

1997

Journal of Biological Chemistry

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Membrane vesicles isolated from the cell envelope of the archaebacterium Haloferax volcanii were either reconstituted in giant liposomes and examined by the patch-clamp technique or were fused into planar lipid bilayers. In addition, cell envelope proteins were solubilized by detergent and reconstituted in azolectin liposomes, which were then fused into planar lipid bilayers. Independently of the technique used the predominant channel activity encountered exhibited the following characteristics. Channels were open at all voltages in the range approximately ؊120 to ؉120 mV and exhibited frequent fast transitions to closed levels of different amplitudes. At voltages greater than 120 mV the channels tended to close in a manner characterized by large, slow transitions of variable amplitudes. The tendency to close at high membrane potentials was much stronger at one polarity. The channel gating pattern was complex exhibiting a range of subconductances of 10 -300 picosiemens in symmetric 100 mM KCl. These electrophysiological characteristics are comparable with those of bacterial and mitochondrial porins, suggesting that the archaeal channels may belong to the general class of porin channels. Some channels showed preference for K ؉ , whereas the others preferred Cl ؊ , suggesting the existence of at least two types of porin-like channels in H. volcanii.

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Section: Resultsmentioning

confidence: 99%

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Besnard

Martinac

Ghazi

1997

Journal of Biological Chemistry

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“…the a-haemolysin of E. coli [148,149]. An ion transporting proteinaceous pore in the cell wall of M. chelonae has been described [150]. This pore has a diameter of 2.2 nm and is much too small to allow the passage of macromolecules, but the discovery of this pathway across the lipid rich permeability barrier will hopefully stimulate further research in the different pathways of cell wall passage in mycobacteria.…”

Section: Culture Filtrate Proteinsmentioning

confidence: 99%

Host Responses and Antigens Involved in Protective Immunity to Mycobacterium tuberculosis

1997

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Andersen P. Host Responses and Antigens Involved in Protective Immunity to Mycobacterium tuberculosis. Scand J Immunol 1997;45:115-131 Tuberculosis (TB) is the largest single infectious cause of human mortality. The incidence of TB has remained high in most of the developing world and the disease has recently re-emerged as a public health problem in industrialized countries. The development of a new improved TB vaccine is a highly prioritized international research area, which has been further stimulated by the appearance of multi-drug resistant strains of Mycobacterium tuberculosis. The present status of the attempts to characterize the protective immune response to TB will be reviewed with special emphasis on recent progress in the identification and characterization of target molecules recognized by protective cells. This paper will focus on proteins released from live bacteria and discuss their role in the host-pathogen interaction and the ongoing attempts to use these molecules in TB subunit vaccines.

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“…Unlike Gram-positive walls, the mycobacterial wall also contains a great variety of other lipids, which are probably arranged to form an asymmetric bilayer with the cell wall mycolate monolayer, but not covalently attached to it (Minnikin, 1982). In addition, pore-forming proteins, typifying Gram-negative bacteria, have been characterized in the walls of several mycobacterial species (Mukhopadhyay et al, 1997 ;Trias et al, 1992, Trias & Benz, 1994Senaratne et al, 1998). Consequently, although mycobacteria are phylogenetically classified as Gram-positive bacteria, their wall is more related to that of Gram-negative micro-organisms (Draper, 1998).…”

Section: Introductionmentioning

confidence: 99%

The impact of the absence of glycopeptidolipids on the ultrastructure, cell surface and cell wall properties, and phagocytosis of Mycobacterium smegmatis

et al. 2002

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Glycopeptidolipids (GPLs) are a class of species-or type-specific mycobacterial lipids and major constituents of the cell envelopes of many non-tuberculous mycobacteria. To determine the function of GPLs in the physiology of these bacteria, a mutant of Mycobacterium smegmatis in which the gene encoding a mycobacterial nonribosomal peptide synthetase has been inactivated by transposon mutagenesis was analysed. Labelling experiments indicated that half of the bacterial GPLs were located on the cell surface and represented 85 % of the surface-exposed lipids of the parent strain whereas the mutant was defective in the production of the GPLs. Compared to the parent smooth morphotype strain, the GPL-deficient mutant strain exhibited a rough colony morphology, an increase of the cell hydrophobicity and formed huge aggregates. As a consequence, the mutant cells were no longer able to bind ruthenium red, as observed by transmission electron microscopy. The altered surface properties of the mutant cells also affected the phagocytosis of individual bacilli by human monocyte-derived macrophages since mutant cells were internalized more rapidly than cells from the parent strain. Nevertheless, no specific release of surface constituents into the culture broth of the mutant was observed, indicating that the cell surface is composed of substances other than GPLs and that these are essential for maintaining the architecture of the outermost layer of the cell envelope. Importantly, the absence of these major extractable lipids of M. smegmatis from the mutant strain has a profound effect on the uptake of the hydrophobic chenodeoxycholate by cells, indicating that GPLs are involved in the cell wall permeability barrier of M. smegmatis. Altogether, these data showed that, in addition to being distinctive markers of numerous mycobacterial species, GPLs play a role in the bacterial phenotype, surface properties and cell wall permeability.

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Porins in the Cell Wall of Mycobacteria

Cited by 204 publications

References 13 publications

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Host Responses and Antigens Involved in Protective Immunity to Mycobacterium tuberculosis

The impact of the absence of glycopeptidolipids on the ultrastructure, cell surface and cell wall properties, and phagocytosis of Mycobacterium smegmatis

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