scholarly journals Arylamine N-Acetyltransferase Is Required for Synthesis of Mycolic Acids and Complex Lipids in Mycobacterium bovis BCG and Represents a Novel Drug Target

2004 ◽  
Vol 199 (9) ◽  
pp. 1191-1199 ◽  
Author(s):  
Sanjib Bhakta ◽  
Gurdyal S. Besra ◽  
Anna M. Upton ◽  
Tanya Parish ◽  
Carolyn Sholto-Douglas-Vernon ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Bovis ◽  
Acid Synthesis ◽  
Mycolic Acid ◽  
Phenotypic Traits ◽  
Mycobacterium Bovis Bcg ◽  
Mycolic Acids ◽  
Altered Cell ◽  
Novel Target ◽  
Unique Cell

Mycolic acids represent a major component of the unique cell wall of mycobacteria. Mycolic acid biosynthesis is inhibited by isoniazid, a key frontline antitubercular drug that is inactivated by mycobacterial and human arylamine N-acetyltransferase (NAT). We show that an in-frame deletion of Mycobacterium bovis BCG nat results in delayed entry into log phase, altered morphology, altered cell wall lipid composition, and increased intracellular killing by macrophages. In particular, deletion of nat perturbs biosynthesis of mycolic acids and their derivatives and increases susceptibility of M. bovis BCG to antibiotics that permeate the cell wall. Phenotypic traits are fully complemented by introduction of Mycobacterium tuberculosis nat. We infer from our findings that NAT is critical to normal mycolic acid synthesis and hence other derivative cell wall components and represents a novel target for antituberculosis therapy. In addition, this is the first report of an endogenous role for NAT in mycobacteria.

scholarly journals Impact of Methoxymycolic Acid Production by Mycobacterium bovis BCG Vaccines

2004 ◽  
Vol 72 (5) ◽  
pp. 2803-2809 ◽  
Author(s):  
Adam Belley ◽  
David Alexander ◽  
Tania Di Pietrantonio ◽  
Manon Girard ◽  
Joses Jones ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Bovis ◽  
Acid Production ◽  
Acid Synthesis ◽  
Permeability Barrier ◽  
Mycolic Acids ◽  
Cell Wall Permeability ◽  
The Impact

ABSTRACT BCG vaccines are a family of closely related daughter strains of an attenuated isolate of Mycobacterium bovis derived by in vitro passage from 1908 to 1921. During subsequent laboratory propagation of the vaccine strain until its lyophilization in 1961, BCG Pasteur underwent at least seven further genomic mutations. The impact of these mutations on the properties of the vaccine is currently unknown. One mutation, a glycine-to-aspartic acid substitution in the mmaA3 gene, occurred between 1927 and 1931 and impairs methoxymycolic acid synthesis in BCG strains obtained from the Pasteur Institute after this period. Mycolic acids of the cell wall are classified into three functional groups (alpha-, methoxy-, and ketomycolic acids), and together these lipids form a highly specialized permeability barrier around the bacterium. To explore the impact of methoxymycolic acid production by BCG strains, we complemented the functional gene of mmaA3 into BCG Denmark and tested a number of in vitro and in vivo phenotypes. Surprisingly, restoration of methoxymycolic acids alone had no effect on cell wall permeability, resistance to antibiotics, or growth in cultured macrophages and C57BL/6 mice. Our results demonstrate that the loss of methoxymycolic acid production did not apparently affect the virulence of BCG strains.

scholarly journals Genome-wide identification of novel genes involved in Corynebacteriales cell envelope biogenesis using Corynebacterium glutamicum as a model

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0240497
Author(s):  
Célia de Sousa-d’Auria ◽  
Florence Constantinesco-Becker ◽  
Patricia Constant ◽  
Maryelle Tropis ◽  
Christine Houssin
Keyword(s):  
Cell Wall ◽  
Corynebacterium Glutamicum ◽  
Acid Metabolism ◽  
Cell Envelope ◽  
Mycolic Acid ◽  
Bioinformatics Analyses ◽  
Mycolic Acids ◽  
Genome Wide ◽  
Altered Cell ◽  
Covalent Complex

Corynebacteriales are Actinobacteria that possess an atypical didermic cell envelope. One of the principal features of this cell envelope is the presence of a large complex made up of peptidoglycan, arabinogalactan and mycolic acids. This covalent complex constitutes the backbone of the cell wall and supports an outer membrane, called mycomembrane in reference to the mycolic acids that are its major component. The biosynthesis of the cell envelope of Corynebacteriales has been extensively studied, in particular because it is crucial for the survival of important pathogens such as Mycobacterium tuberculosis and is therefore a key target for anti-tuberculosis drugs. In this study, we explore the biogenesis of the cell envelope of Corynebacterium glutamicum, a non-pathogenic Corynebacteriales, which can tolerate dramatic modifications of its cell envelope as important as the loss of its mycomembrane. For this purpose, we used a genetic approach based on genome-wide transposon mutagenesis. We developed a highly effective immunological test based on the use of anti-cell wall antibodies that allowed us to rapidly identify bacteria exhibiting an altered cell envelope. A very large number (10,073) of insertional mutants were screened by means of this test, and 80 were finally selected, representing 55 different loci. Bioinformatics analyses of these loci showed that approximately 60% corresponded to genes already characterized, 63% of which are known to be directly involved in cell wall processes, and more specifically in the biosynthesis of the mycoloyl-arabinogalactan-peptidoglycan complex. We identified 22 new loci potentially involved in cell envelope biogenesis, 76% of which encode putative cell envelope proteins. A mutant of particular interest was further characterized and revealed a new player in mycolic acid metabolism. Because a large proportion of the genes identified by our study is conserved in Corynebacteriales, the library described here provides a new resource of genes whose characterization could lead to a better understanding of the biosynthesis of the envelope components of these bacteria.

scholarly journals Genome-wide identification of novel genes involved in Corynebacteriales cell envelope biogenesis using Corynebacterium glutamicum as a model

2020 ◽  
Author(s):  
Célia de Sousa-d’Auria ◽  
Florence Constantinesco-Becker ◽  
Patricia Constant ◽  
Maryelle Tropis ◽  
Christine Houssin
Keyword(s):  
Cell Wall ◽  
Corynebacterium Glutamicum ◽  
Acid Metabolism ◽  
Cell Envelope ◽  
Mycolic Acid ◽  
Bioinformatics Analyses ◽  
Mycolic Acids ◽  
Genome Wide ◽  
Altered Cell ◽  
Covalent Complex

AbstractCorynebacteriales are Actinobacteria that possess an atypical didermic cell envelope. One of the principal features of this cell envelope is the presence of a large complex made up of peptidoglycan, arabinogalactan and mycolic acids. This covalent complex constitutes the backbone of the cell wall and supports an outer membrane, called mycomembrane in reference to the mycolic acids that are its major component. The biosynthesis of the cell envelope of Corynebacteriales has been extensively studied, in particular because it is crucial for the survival of important pathogens such as Mycobacterium tuberculosis and is therefore a key target for anti-tuberculosis drugs. In this study, we explore the biogenesis of the cell envelope of Corynebacterium glutamicum, a non-pathogenic Corynebacteriales, which can tolerate dramatic modifications of its cell envelope as important as the loss of its mycomembrane. For this purpose, we used a genetic approach based on genome-wide transposon mutagenesis. We developed a highly effective immunological test based on the use of anti-arabinogalactan antibodies that allowed us to rapidly identify bacteria exhibiting an altered cell envelope. A very large number (10,073) of insertional mutants were screened by means of this test, and 80 were finally selected, representing 55 different loci. Bioinformatics analyses of these loci showed that approximately 60% corresponded to genes already characterized, 63% of which are known to be directly involved in cell wall processes, and more specifically in the biosynthesis of the mycoloyl-arabinogalactan-peptidoglycan complex. We identified 22 new loci potentially involved in cell envelope biogenesis, 76% of which encode putative cell envelope proteins. A mutant of particular interest was further characterized and revealed a new player in mycolic acid metabolism. Because a large proportion of the genes identified by our study is conserved in Corynebacteriales, the library described here provides a new resource of genes whose characterization could lead to a better understanding of the biosynthesis of the envelope components of these bacteria.

scholarly journals Maturation of Human Dendritic Cells by Cell Wall Skeleton of Mycobacterium bovis Bacillus Calmette-Guérin: Involvement of Toll-Like Receptors

2000 ◽  
Vol 68 (12) ◽  
pp. 6883-6890 ◽  
Author(s):  
Shoutaro Tsuji ◽  
Misako Matsumoto ◽  
Osamu Takeuchi ◽  
Shizuo Akira ◽  
Ichiro Azuma ◽  
...  
Keyword(s):  
Cell Wall ◽  
Dendritic Cells ◽  
Mycobacterium Bovis ◽  
Surface Expression ◽  
Necrosis Factor Alpha ◽  
Mycolic Acids ◽  
Tnf Α ◽  
Toll Like Receptor 2 ◽  
Factor Alpha ◽  
Human Dendritic Cells

ABSTRACT The constituents of mycobacteria are an effective immune adjuvant, as observed with complete Freund's adjuvant. In this study, we demonstrated that the cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guérin (BCG-CWS), a purified noninfectious material consisting of peptidoglycan, arabinogalactan, and mycolic acids, induces maturation of human dendritic cells (DC). Surface expression of CD40, CD80, CD83, and CD86 was increased by BCG-CWS on human immature DC, and the effect was similar to those of interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), heat-killed BCG, and viable BCG. BCG-CWS induced the secretion of TNF-α, IL-6, and IL-12 p40. CD83 expression was increased by a soluble factor secreted from BCG-CWS-treated DC and was completely inhibited by monoclonal antibodies against TNF-α. BCG-CWS-treated DC stimulated extensive allogeneic mixed lymphocyte reactions. The level of TNF-α secreted through BCG-CWS was partially suppressed in murine macrophages with no Toll-like receptor 2 (TLR 2) or TLR4 and was completely lost in TLR2 and TLR4 double-deficient macrophages. These results suggest that the BCG-CWS induces TNF-α secretion from DC via TLR2 and TLR4 and that the secreted TNF-α induces the maturation of DC per se.

scholarly journals Carbon Source-Induced Modifications in the Mycolic Acid Content and Cell Wall Permeability of Rhodococcus erythropolis E1

2003 ◽  
Vol 69 (12) ◽  
pp. 7019-7027 ◽  
Author(s):  
Ivana Sokolovská ◽  
Raoul Rozenberg ◽  
Christophe Riez ◽  
Paul G. Rouxhet ◽  
Spiros N. Agathos ◽  
...  
Keyword(s):  
Cell Wall ◽  
Carbon Source ◽  
Acid Content ◽  
Rhodococcus Erythropolis ◽  
Mycolic Acid ◽  
Mycolic Acids ◽  
Carbon Chains ◽  
Linear Alkanes ◽  
Wall Permeability ◽  
Cell Wall Permeability

ABSTRACT The influence of the carbon source on cell wall properties was analyzed in an efficient alkane-degrading strain of Rhodococcus erythropolis (strain E1), with particular focus on the mycolic acid content. A clear correlation was observed between the carbon source and the mycolic acid profiles as estimated by high-performance liquid chromatography and mass spectrometry. Two types of mycolic acid patterns were observed after growth either on saturated linear alkanes or on short-chain alkanoates. One type of pattern was characterized by the lack of odd-numbered carbon chains and resulted from growth on linear alkanes with even numbers of carbon atoms. The second type of pattern was characterized by mycolic acids with both even- and odd-numbered carbon chains and resulted from growth on compounds with odd-numbered carbon chains, on branched alkanes, or on mixtures of different compounds. Cellular short-chain fatty acids were twice as abundant during growth on a branched alkane (pristane) as during growth on acetate, while equal amounts of mycolic acids were found under both conditions. More hydrocarbon-like compounds and less polysaccharide were exposed at the cell wall surface during growth on alkanes. Whatever the substrate, the cells had the same affinity for aqueous-nonaqueous solvent interfaces. By contrast, bacteria displayed completely opposite susceptibilities to hydrophilic and hydrophobic antibiotics and were found to be strongly stained by hydrophobic dyes after growth on pristane but not after growth on acetate. Taken together, these data show that the cell wall composition of R. erythropolis E1 is influenced by the nutritional regimen and that the most marked effect is a radical change in cell wall permeability.

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