PE/PPE proteins mediate nutrient transport across the outer membrane of Mycobacterium tuberculosis

Science ◽  
2020 ◽  
Vol 367 (6482) ◽  
pp. 1147-1151 ◽  
Author(s):  
Qinglan Wang ◽  
Helena I. M. Boshoff ◽  
Justin R. Harrison ◽  
Peter C. Ray ◽  
Simon R. Green ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Outer Membrane ◽  
Nutrient Transport ◽  
Low Permeability ◽  
Cell Wall Component ◽  
Phthiocerol Dimycocerosate ◽  
Porin Proteins ◽  
Dependent Growth ◽  
Mycobacterial Cell Wall

Mycobacterium tuberculosis has an unusual outer membrane that lacks canonical porin proteins for the transport of small solutes to the periplasm. We discovered that 3,3-bis-di(methylsulfonyl)propionamide (3bMP1) inhibits the growth of M. tuberculosis, and resistance to this compound is conferred by mutation within a member of the proline-proline-glutamate (PPE) family, PPE51. Deletion of PPE51 rendered M. tuberculosis cells unable to replicate on propionamide, glucose, or glycerol. Growth was restored upon loss of the mycobacterial cell wall component phthiocerol dimycocerosate. Mutants in other proline-glutamate (PE)/PPE clusters, responsive to magnesium and phosphate, also showed a phthiocerol dimycocerosate–dependent growth compromise upon limitation of the corresponding substrate. Phthiocerol dimycocerosate determined the low permeability of the mycobacterial outer membrane, and the PE/PPE proteins apparently act as solute-specific channels.

Molecular Structure of the Outermost Cell Wall Component of Spirillum Serpens

1977 ◽  
Vol 35 ◽  
pp. 342-343
Author(s):  
Wah Chiu ◽  
David Grano
Keyword(s):  
Molecular Structure ◽  
Cell Wall ◽  
Outer Membrane ◽  
Gel Electrophoresis ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Cell Wall Component ◽  
Protein Components ◽  
Exposure Technique ◽  
Structural Aspects

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.

Expression of a long pentraxin, PTX3, by monocytes exposed to the mycobacterial cell wall component lipoarabinomannan.

1997 ◽  
Vol 65 (4) ◽  
pp. 1345-1350 ◽  
Author(s):  
V Vouret-Craviari ◽  
C Matteucci ◽  
G Peri ◽  
G Poli ◽  
M Introna ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Wall Component ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall

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

scholarly journals Mycobacterium tuberculosis Lipomannan Induces Apoptosis and Interleukin-12 Production in Macrophages

2004 ◽  
Vol 72 (4) ◽  
pp. 2067-2074 ◽  
Author(s):  
D. N. Dao ◽  
L. Kremer ◽  
Y. Guérardel ◽  
A. Molano ◽  
W. R. Jacobs ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Function Analysis ◽  
Specific Interaction ◽  
Interleukin 12 ◽  
Mycobacterial Species ◽  
Immunostimulatory Activity ◽  
Mycobacterium Chelonae ◽  
Toll Like Receptor 2 ◽  
Mycobacterial Cell Wall

ABSTRACT The mycobacterial cell wall component lipoarabinomannan (LAM) has been described as a virulence factor of Mycobacterium tuberculosis, and modification of the terminal arabinan residues of this compound with mannose caps (producing mannosyl-capped LAM [ManLAM]) in M. tuberculosis or with phosphoinositol caps (producing phosphoinositol-capped LAM [PILAM]) in Mycobacterium smegmatis has been implicated in various functions associated with these lipoglycans. A structure-function analysis was performed by using LAMs and their biosynthetic precursor lipomannans (LMs) isolated from different mycobacterial species on the basis of their capacity to induce the production of interleukin-12 (IL-12) and/or apoptosis of macrophage cell lines. Independent of the mycobacterial species, ManLAMs did not induce IL-12 gene expression or apoptosis of macrophages, whereas PILAMs induced IL-12 secretion and apoptosis. Interestingly, uncapped LAM purified from Mycobacterium chelonae did not induce IL-12 secretion or apoptosis. Furthermore, LMs, independent of their mycobacterial origins, were potent inducers of IL-12 and apoptosis. The precursor of LM, phosphatidyl-myo-inositol dimannoside, had no activity, suggesting that the mannan core of LM was required for the activity of LM. The specific interaction of LM with Toll-like receptor 2 (TLR-2) but not with TLR-4 suggested that these responses were mediated via the TLR-2 signaling pathway. Our experiments revealed an important immunostimulatory activity of the biosynthetic LAM precursor LM. The ratio of LAM to LM in the cell wall of mycobacteria may be an important determinant of virulence, and enzymes that modify LM could provide targets for development of antituberculosis drugs and for derivation of attenuated strains of M. tuberculosis.

scholarly journals Multiple Mutations in Mycobacterium tuberculosis MmpL3 Increase Resistance to MmpL3 Inhibitors

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Matthew B. McNeil ◽  
Theresa O’Malley ◽  
Devon Dennison ◽  
Catherine D. Shelton ◽  
Bjorn Sunde ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Drug Targets ◽  
New Drugs ◽  
Content Type ◽  
Mechanism Of Resistance ◽  
Primary Mechanism ◽  
Resistant Mutants ◽  
Mycobacterial Cell Wall

ABSTRACT The Mycobacterium tuberculosis protein MmpL3 performs an essential role in cell wall synthesis, since it effects the transport of trehalose monomycolates across the inner membrane. Numerous structurally diverse pharmacophores have been identified as inhibitors of MmpL3 largely based on the identification of resistant isolates with mutations in MmpL3. For some compounds, it is possible there are different primary or secondary targets. Here, we have investigated resistance to the spiral amine class of compounds. Isolation and sequencing of resistant mutants demonstrated that all had mutations in MmpL3. We hypothesized that if additional targets of this pharmacophore existed, then successive rounds to generate resistant isolates might reveal mutations in other loci. Since compounds were still active against resistant isolates, albeit with reduced potency, we isolated resistant mutants in this background at higher concentrations. After a second round of isolation with the spiral amine, we found additional mutations in MmpL3. To increase our chance of finding alternative targets, we ran a third round of isolation using a different molecule scaffold (AU1235, an adamantyl urea). Surprisingly, we obtained further mutations in MmpL3. Multiple mutations in MmpL3 increased the level and spectrum of resistance to different pharmacophores but did not incur a fitness cost in vitro. These results support the hypothesis that MmpL3 is the primary mechanism of resistance and likely target for these pharmacophores. IMPORTANCE Mycobacterium tuberculosis is a major global human pathogen, and new drugs and new drug targets are urgently required. Cell wall biosynthesis is a major target of current tuberculosis drugs and of new agents under development. Several new classes of molecules appear to have the same target, MmpL3, which is involved in the export and synthesis of the mycobacterial cell wall. However, there is still debate over whether MmpL3 is the primary or only target for these classes. We wanted to confirm the mechanism of resistance for one series. We identified mutations in MmpL3 which led to resistance to the spiral amine series. High-level resistance to these compounds and two other series was conferred by multiple mutations in the same protein (MmpL3). These mutations did not reduce growth rate in culture. These results support the hypothesis that MmpL3 is the primary mechanism of resistance and likely target for these pharmacophores.

scholarly journals Synthesis and Biological Aspects of Mycolic Acids: An Important Target AgainstMycobacterium tuberculosis

2008 ◽  
Vol 8 ◽  
pp. 720-751 ◽  
Author(s):  
Marcus Vinícius Nora de Souza ◽  
Marcelle de Lima Ferreira ◽  
Alessandra Campbell Pinheiro ◽  
Maurício Frota Saraiva ◽  
Mauro Vieira de Almeida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Cell Walls ◽  
Important Class ◽  
Cellular Targets ◽  
Mycolic Acids ◽  
Important Target ◽  
Novel Drugs ◽  
Biological Aspects ◽  
Mycobacterial Cell Wall

Mycolic acids are an important class of compounds, basically found in the cell walls of a group of bacteria known as mycolata taxon, exemplified by the most famous bacteria of this group, theMycobacterium tuberculosis(M. tb.), the agent responsible for the disease known as tuberculosis (TB). Mycolic acids are important for the survival of M. tb. For example, they are able to help fight against hydrophobic drugs and dehydration, and also allow this bacterium to be more effective in the host's immune system by growing inside macrophages. Due to the importance of the mycolic acids for maintenance of the integrity of the mycobacterial cell wall, these compounds become attractive cellular targets for the development of novel drugs against TB. In this context, the aim of this article is to highlight the importance of mycolic acids in drug discovery.

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 Functional Complementation of the Essential Gene fabG1 of Mycobacterium tuberculosis by Mycobacterium smegmatis fabG but Not Escherichia coli fabG

2007 ◽  
Vol 189 (10) ◽  
pp. 3721-3728 ◽  
Author(s):  
Tanya Parish ◽  
Gretta Roberts ◽  
Francoise Laval ◽  
Merrill Schaeffer ◽  
Mamadou Daffé ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Essential Gene ◽  
Permeability Barrier ◽  
Type I ◽  
Type Ii ◽  
Mycolic Acids ◽  
Mycobacterial Cell Wall

ABSTRACT Mycolic acids are a key component of the mycobacterial cell wall, providing structure and forming a major permeability barrier. In Mycobacterium tuberculosis mycolic acids are synthesized by type I and type II fatty acid synthases. One of the enzymes of the type II system is encoded by fabG1. We demonstrate here that this gene can be deleted from the M. tuberculosis chromosome only when another functional copy is provided elsewhere, showing that under normal culture conditions fabG1 is essential. FabG1 activity can be replaced by the corresponding enzyme from the closely related species Mycobacterium smegmatis but not by the enzyme from Escherichia coli. M. tuberculosis carrying FabG from M. smegmatis showed no phenotypic changes, and both the mycolic acids and cell wall permeability were unchanged. Thus, M. tuberculosis and M. smegmatis enzymes are interchangeable and do not control the lengths and types of mycolic acids synthesized.

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