Structure of the Mycobacterium tuberculosis OmpATb protein: A model of an oligomeric channel in the mycobacterial cell wall

2010 ◽  
Vol 79 (2) ◽  
pp. 645-661 ◽  
Author(s):  
Yinshan Yang ◽  
Daniel Auguin ◽  
Stéphane Delbecq ◽  
Emilie Dumas ◽  
Gérard Molle ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Protein A ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall

Identification of inhibitors targeting Mycobacterium tuberculosis cell wall biosynthesis via dynamic combinatorial chemistry

2017 ◽  
Vol 53 (77) ◽  
pp. 10632-10635 ◽  
Author(s):  
Jian Fu ◽  
Huixiao Fu ◽  
Marc Dieu ◽  
Iman Halloum ◽  
Laurent Kremer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Combinatorial Chemistry ◽  
Cell Wall Biosynthesis ◽  
Combinatorial Approach ◽  
Dynamic Combinatorial Chemistry ◽  
Mycobacterial Cell ◽  
Essential Enzyme ◽  
Mycobacterial Cell Wall

In this study, we report a dynamic combinatorial approach along with highly efficient in situ screening to identify inhibitors of UDP-galactopyranose mutase (UGM), an essential enzyme involved in mycobacterial cell wall biosynthesis.

scholarly journals Critical Roles for Lipomannan and Lipoarabinomannan in Cell Wall Integrity of Mycobacteria and Pathogenesis of Tuberculosis

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Takeshi Fukuda ◽  
Takayuki Matsumura ◽  
Manabu Ato ◽  
Maho Hamasaki ◽  
Yukiko Nishiuchi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Critical Role ◽  
Protective Role ◽  
Cell Wall Integrity ◽  
Structural Defects ◽  
Wall Structure ◽  
Content Type ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall

ABSTRACTLipomannan (LM) and lipoarabinomannan (LAM) are mycobacterial glycolipids containing a long mannose polymer. While they are implicated in immune modulations, the significance of LM and LAM as structural components of the mycobacterial cell wall remains unknown. We have previously reported that a branch-forming mannosyltransferase plays a critical role in controlling the sizes of LM and LAM and that deletion or overexpression of this enzyme results in gross changes in LM/LAM structures. Here, we show that such changes in LM/LAM structures have a significant impact on the cell wall integrity of mycobacteria. InMycobacterium smegmatis, structural defects in LM and LAM resulted in loss of acid-fast staining, increased sensitivity to β-lactam antibiotics, and faster killing by THP-1 macrophages. Furthermore, equivalentMycobacterium tuberculosismutants became more sensitive to β-lactams, and one mutant showed attenuated virulence in mice. Our results revealed previously unknown structural roles for LM and LAM and further demonstrated that they are important for the pathogenesis of tuberculosis.IMPORTANCETuberculosis (TB) is a global burden, affecting millions of people worldwide.Mycobacterium tuberculosisis a causative agent of TB, and understanding the biology ofM. tuberculosisis essential for tackling this devastating disease. The cell wall ofM. tuberculosisis highly impermeable and plays a protective role in establishing infection. Among the cell wall components, LM and LAM are major glycolipids found in allMycobacteriumspecies, show various immunomodulatory activities, and have been thought to play roles in TB pathogenesis. However, the roles of LM and LAM as integral parts of the cell wall structure have not been elucidated. Here we show that LM and LAM play critical roles in the integrity of mycobacterial cell wall and the pathogenesis of TB. These findings will now allow us to seek the possibility that the LM/LAM biosynthetic pathway is a chemotherapeutic target.

scholarly journals An Inhibitor of Exported Mycobacterium tuberculosis Glutamine Synthetase Selectively Blocks the Growth of Pathogenic Mycobacteria in Axenic Culture and in Human Monocytes: Extracellular Proteins as Potential Novel Drug Targets

1999 ◽  
Vol 189 (9) ◽  
pp. 1425-1436 ◽  
Author(s):  
Günter Harth ◽  
Marcus A. Horwitz
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Glutamine Synthetase ◽  
Extracellular Proteins ◽  
Mononuclear Phagocytes ◽  
Cell Wall Structure ◽  
Host Cells ◽  
Wall Structure ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall

Mycobacterium tuberculosis and other pathogenic mycobacteria export abundant quantities of proteins into their extracellular milieu when growing either axenically or within phagosomes of host cells. One major extracellular protein, the enzyme glutamine synthetase, is of particular interest because of its link to pathogenicity. Pathogenic mycobacteria, but not nonpathogenic mycobacteria, export large amounts of this protein. Interestingly, export of the enzyme is associated with the presence of a poly-l-glutamate/glutamine structure in the mycobacterial cell wall. In this study, we investigated the influence of glutamine synthetase inhibitors on the growth of pathogenic and nonpathogenic mycobacteria and on the poly-l-glutamate/glutamine cell wall structure. The inhibitor l-methionine-S-sulfoximine rapidly inactivated purified M. tuberculosis glutamine synthetase, which was 100-fold more sensitive to this inhibitor than a representative mammalian glutamine synthetase. Added to cultures of pathogenic mycobacteria, l-methionine- S-sulfoximine rapidly inhibited extracellular glutamine synthetase in a concentration-dependent manner but had only a minimal effect on cellular glutamine synthetase, a finding consistent with failure of the drug to cross the mycobacterial cell wall. Remarkably, the inhibitor selectively blocked the growth of pathogenic mycobacteria, all of which release glutamine synthetase extracellularly, but had no effect on nonpathogenic mycobacteria or nonmycobacterial microorganisms, none of which release glutamine synthetase extracellularly. The inhibitor was also bacteriostatic for M. tuberculosis in human mononuclear phagocytes (THP-1 cells), the pathogen's primary host cells. Paralleling and perhaps underlying its bacteriostatic effect, the inhibitor markedly reduced the amount of poly-l-glutamate/glutamine cell wall structure in M. tuberculosis. Although it is possible that glutamine synthetase inhibitors interact with additional extracellular proteins or structures, our findings support the concept that extracellular proteins of M. tuberculosis and other pathogenic mycobacteria are worthy targets for new antibiotics. Such proteins constitute readily accessible targets of these relatively impermeable organisms, which are rapidly developing resistance to conventional antibiotics.

scholarly journals Galactosyl Transferases in Mycobacterial Cell Wall Synthesis

2007 ◽  
Vol 190 (3) ◽  
pp. 1141-1145 ◽  
Author(s):  
Martina Beláňová ◽  
Petronela Dianišková ◽  
Patrick J. Brennan ◽  
Gladys C. Completo ◽  
Natisha L. Rose ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Cell Wall Synthesis ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall ◽  
Natural And Synthetic

ABSTRACT Two galactosyl transferases can apparently account for the full biosynthesis of the cell wall galactan of mycobacteria. Evidence is presented based on enzymatic incubations with purified natural and synthetic galactofuranose (Galf) acceptors that the recombinant galactofuranosyl transferase, GlfT1, from Mycobacterium smegmatis, the Mycobacterium tuberculosis Rv3782 ortholog known to be involved in the initial steps of galactan formation, harbors dual β-(1→4) and β-(1→5) Galf transferase activities and that the product of the enzyme, decaprenyl-P-P-GlcNAc-Rha-Galf-Galf, serves as a direct substrate for full polymerization catalyzed by another bifunctional Galf transferase, GlfT2, the Rv3808c enzyme.

scholarly journals Lcp1 Is a Phosphotransferase Responsible for Ligating Arabinogalactan to Peptidoglycan in Mycobacterium tuberculosis

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
James Harrison ◽  
Georgina Lloyd ◽  
Maju Joe ◽  
Todd L. Lowary ◽  
Edward Reynolds ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Essential Gene ◽  
Cell Envelope ◽  
New Drugs ◽  
Cell Wall Assembly ◽  
Mycobacterial Cell ◽  
Unique Cell ◽  
Mycobacterial Cell Wall ◽  
Wall Assembly

ABSTRACT Mycobacterium tuberculosis , the etiological agent of tuberculosis (TB), has a unique cell envelope which accounts for its unusual low permeability and contributes to resistance against common antibiotics. The main structural elements of the cell wall consist of a cross-linked network of peptidoglycan (PG) in which some of the muramic acid residues are covalently attached to a complex polysaccharide, arabinogalactan (AG), via a unique α- l -rhamnopyranose–(1→3)-α- d -GlcNAc-(1→P) linker unit. While the molecular genetics associated with PG and AG biosynthetic pathways have been largely delineated, the mechanism by which these two major pathways converge has remained elusive. In Gram-positive organisms, the LytR-CpsA-Psr (LCP) family of proteins are responsible for ligating cell wall teichoic acids to peptidoglycan, through a linker unit that bears a striking resemblance to that found in mycobacterial arabinogalactan. In this study, we have identified Rv3267 as a mycobacterial LCP homolog gene that encodes a phosphotransferase which we have named Lcp1. We demonstrate that lcp1 is an essential gene required for cell viability and show that recombinant Lcp1 is capable of ligating AG to PG in a cell-free radiolabeling assay. IMPORTANCE Tuberculosis is an infectious disease caused by the bacterial organism Mycobacterium tuberculosis . Survival of M. tuberculosis rests critically on the integrity of its unique cell wall; therefore, a better understanding of how the genes and enzymes involved in cell wall assembly work is fundamental for us to develop new drugs to treat this disease. In this study, we have identified Lcp1 as an essential phosphotransferase that ligates together arabinogalactan and peptidoglycan, two crucial cell wall macromolecules found within the mycobacterial cell wall. The discovery of Lcp1 sheds new light on the final stages of mycobacterial cell wall assembly and represents a key biosynthetic step that could be exploited for new anti-TB drug discovery.

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