scholarly journals FbpA-Dependent Biosynthesis of Trehalose Dimycolate Is Required for the Intrinsic Multidrug Resistance, Cell Wall Structure, and Colonial Morphology of Mycobacterium smegmatis

2005 ◽  
Vol 187 (19) ◽  
pp. 6603-6611 ◽  
Author(s):  
Liem Nguyen ◽  
Satheesh Chinnapapagari ◽  
Charles J. Thompson
Keyword(s):  
Cell Wall ◽  
Antibiotic Resistance ◽  
Mycobacterium Smegmatis ◽  
Mycolic Acid ◽  
Wall Structure ◽  
Single Mutation ◽  
Mycolic Acids ◽  
Trehalose Dimycolate ◽  
Colonial Morphology ◽  
Mycobacterial Cell Wall

ABSTRACT Ligation of mycolic acids to structural components of the mycobacterial cell wall generates a hydrophobic, impermeable barrier that provides resistance to toxic compounds such as antibiotics. Secreted proteins FbpA, FbpB, and FbpC attach mycolic acids to arabinogalactan, generating mycolic acid methyl esters (MAME) or trehalose, generating α,α′-trehalose dimycolate (TDM; also called cord factor). Our studies of Mycobacterium smegmatis showed that disruption of fbpA did not affect MAME levels but resulted in a 45% reduction of TDM. The fbpA mutant displayed increased sensitivity to both front-line tuberculosis-targeted drugs as well as other broad-spectrum antibiotics widely used for antibacterial chemotherapy. The irregular, hydrophobic surface of wild-type M. smegmatis colonies became hydrophilic and smooth in the mutant. While expression of M. smegmatis fbpA restored defects of the mutant, heterologous expression of the Mycobacterium tuberculosis fbpA gene was less effective. A single mutation in the M. smegmatis FbpA esterase domain inactivated its ability to provide antibiotic resistance. These data show that production of TDM by FbpA is essential for the intrinsic antibiotic resistance and normal colonial morphology of some mycobacteria and support the concept that FbpA-specific inhibitors, alone or in combination with other antibiotics, could provide an effective treatment to tuberculosis and other mycobacterial diseases.

scholarly journals Mycobacteriophage Ms6 LysB specifically targets the outer membrane of Mycobacterium smegmatis

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1497-1504 ◽  
Author(s):  
Filipa Gil ◽  
Anna E. Grzegorzewicz ◽  
Maria João Catalão ◽  
João Vital ◽  
Michael R. McNeil ◽  
...  
Keyword(s):  
Cell Wall ◽  
Outer Membrane ◽  
Mycobacterium Smegmatis ◽  
Mycolic Acid ◽  
Head Group ◽  
Lipolytic Enzyme ◽  
Ester Bond ◽  
Mycolic Acids ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall

LysB, a mycobacteriophage Ms6-encoded protein, was previously identified as a lipolytic enzyme able to hydrolyse the ester bond in lipase and esterase substrates. In the present work, we show that LysB can hydrolyse lipids containing mycolic acids from the outer membrane of the mycobacterial cell wall. LysB was shown to hydrolyse the mycolic acids from the mycolyl-arabinogalactan–peptidoglycan complex where the mycolates of the inner leaflet of the outer membrane are covalently attached to an arabinosyl head group. In addition, treatment of the extractable lipids from Mycobacterium smegmatis, Mycobacterium bovis BCG and Mycobacterium tuberculosis H37Ra with LysB showed that trehalose 6,6′-dimycolate (TDM), a trehalose diester of two mycolic acid molecules, was hydrolysed by the enzyme. We have also determined the structures of the mycolic acid molecules that form the M. smegmatis TDM. The identification of a phage-encoded enzyme that targets the outer membrane of the mycobacterial cell wall enhances our understanding of the mechanism of mycobacteriophage lysis.

scholarly journals The aceE involves in mycolic acid synthesis and biofilm formation in Mycobacterium smegmatis

2020 ◽  
Author(s):  
Suting Chen ◽  
Tianlu Teng ◽  
Shuan Wen ◽  
Tingting Zhang ◽  
Hairong Huang
Keyword(s):  
Cell Wall ◽  
Biofilm Formation ◽  
Morphological Changes ◽  
Acid Synthesis ◽  
Mycolic Acid ◽  
Colony Morphology ◽  
Wall Structure ◽  
Wild Type ◽  
Mycobacterial Cell Wall

Abstract Background: The integrity of cell wall structure is highly significant for the in vivo survival for mycobacteria. However, the mechanisms underlying the biosynthesis of mycobacterial cell wall remain poorly understood. aceE encodes the E1 component of pyruvate dehydrogenase (PDH)complex. This study aimed to know the functional role of aceE gene in cell wall biosynthesis in M. smegmatis.Results: We observed that the colony morphology of aceE-deficient mutants(aceE-mut)was quite different from the wild-type(WT) strain during the transposon library screening of M.smegmatis, smaller and smoother on the solid culture medium. Notably, the aceE-mut lost its ability of growing aggregately and biofilm forming, which are two very important features of mycobacteria.The morphological changes of the aceE-mut strain were further confirmed by electron microscopy that presented shorter, smoother and thinner images in contrast withWT strain.Additionally, the analysis of mycolic acid(MA)using LC-MS indicated deficiency of alpha-MA and epoxy-MA in aceE-mut strain whereas complementation of the aceE-mut with a wild-type aceEgene restored the composition of MA. Conclusions: Overall, this study indicates that aceE gene plays a significant role in the mycolic acid synthesis and affects the colony morphology and biofilm formation of M.smegmatis.

scholarly journals Cell Wall Core Galactofuran Synthesis Is Essential for Growth of Mycobacteria

2001 ◽  
Vol 183 (13) ◽  
pp. 3991-3998 ◽  
Author(s):  
Fei Pan ◽  
Mary Jackson ◽  
Yufang Ma ◽  
Michael McNeil
Keyword(s):  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Mycolic Acid ◽  
Separate Experiment ◽  
Temperature Sensitive ◽  
Origin Of Replication ◽  
Knockout Mutant ◽  
Allelic Replacement ◽  
Higher Temperature ◽  
Mycobacterial Cell Wall

ABSTRACT The mycobacterial cell wall core consists of an outer lipid (mycolic acid) layer attached to peptidoglycan via a galactofuranosyl-containing polysaccharide, arabinogalactan. This structural arrangement strongly suggests that galactofuranosyl residues are essential for the growth and viability of mycobacteria. Galactofuranosyl residues are formed in nature by a ring contraction of UDP-galactopyranose to UDP-galactofuranose catalyzed by the enzyme UDP-galactopyranose mutase (Glf). In Mycobacterium tuberculosis the glf gene overlaps, by 1 nucleotide, a gene, Rv3808c, that has been shown to encode a galactofuranosyl transferase. We demonstrate here thatglf can be knocked out in Mycobacterium smegmatis by allelic replacement only in the presence of two rescue plasmids carrying functional copies of glf and Rv3808c. The glf rescue plasmid was designed with a temperature-sensitive origin of replication and the M. smegmatis glf knockout mutant is unable to grow at the higher temperature at which the glf-containing rescue plasmid is lost. In a separate experiment, the Rv3808c rescue plasmid was designed with a temperature-sensitive origin of replication and theglf-bearing plasmid was designed with a normal original of replication; this strain was also unable to grow at the nonpermissive temperature. Thus, both glf and Rv3808c are essential for growth. These findings and the fact that galactofuranosyl residues are not found in humans supports the development of UDP-galactopyranose mutase and galactofuranosyl transferase as important targets for the development of new antituberculosis drugs.

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.

scholarly journals Synthesis of a homologous series of galactofuranose-containing mycobacterial arabinogalactan fragments

2016 ◽  
Vol 94 (11) ◽  
pp. 976-988 ◽  
Author(s):  
Maju Joe ◽  
Todd L. Lowary
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Chemical Synthesis ◽  
Mycolic Acid ◽  
Wall Structure ◽  
Complex Cell ◽  
Human Pathogen ◽  
Structural Element ◽  
Target Molecules ◽  
Mycobacterial Cell Wall

Mycobacteria, including the human pathogen Mycobacterium tuberculosis, the causative agent of tuberculosis, produce a complex cell wall structure made of carbohydrates and lipids. The major structural element of the mycobacterial cell wall is a glycoconjugate called the mycolic acid – arabinogalactan – peptidoglycan (mAGP) complex. Inhibition of mAGP biosynthesis is a proven strategy for developing anti-mycobacterial drugs, and thus, understanding the pathways and enzymes involved in the assembly of this molecule is of interest. In this paper, we describe the chemical synthesis of a panel of nine oligosaccharide fragments (4–12) of the galactan domain of the mAGP complex designed as biosynthetic probes. These structures, ranging in size from a hexasaccharide to a tetradecasaccharide, are potential substrates for two biosynthetic enzymes, GlfT2 and AftA, and represent the largest mycobacterial galactan fragments synthesized to date. The route developed was iterative and provided multimilligram quantities of the target molecules 4–12 in good overall yield.

scholarly journals The aceE involves in mycolic acid synthesis and biofilm formation in Mycobacterium smegmatis

2020 ◽  
Author(s):  
Suting Chen ◽  
Tianlu Teng ◽  
Shuan Wen ◽  
Tingting Zhang ◽  
Hairong Huang
Keyword(s):  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Biofilm Formation ◽  
Morphological Changes ◽  
Acid Synthesis ◽  
Mycolic Acid ◽  
Colony Morphology ◽  
Wall Structure ◽  
Wild Type

Abstract Background: The integrity of cell wall structure is highly significant for the in vivo survival of mycobacteria. We hypothesized that changes in morphology may indicate changes in cell wall metabolism and identified an aceE gene mutant ( aceE -mut) which presented a deficient colony morphology on 7H10 agar by screening transposon mutagenesis in Mycolicibacterium smegmatis , basonym Mycobacterium smegmatis ( M. smegmatis ). This study aimed to identify the functional role of aceE gene in cell wall biosynthesis in M. smegmatis. Results: We observed that the colony morphology of aceE -mut was quite different, smaller and smoother on the solid culture medium than the wild-type (WT) strain during the transposon library screening of M. smegmatis . Notably, in contrast with the WT, which aggregates and forms biofilm, the aceE -mut lost its ability of growing aggregately and biofilm formation, which are two very important features of mycobacteria. The morphological changes in the aceE -mut strain were further confirmed by electron microscopy which indicated smoother and thinner cell envelope images in contrast with the rough morphology of WT strains. Additionally, the aceE -mut was more fragile to acidic stress and exhibited a pronounced defects in entering the macrophages as compared to the WT. The analysis of mycolic acid (MA) using LC-MS indicated deficiency of alpha-MA and epoxy-MA in aceE -mut strain whereas complementation of the aceE -mut with a wild-type aceE gene restored the composition of MA. Conclusions: Over all, this study indicates that aceE gene plays a significant role in the mycolic acid synthesis and affects the colony morphology, biofilm formation of M. smegmatis and bacteria invasion of macrophage.

scholarly journals Rifampicin or capreomycin induced remodelling of the Mycobacterium smegmatis mycolic acid layer is mitigated in synergistic combinations with cationic antimicrobial peptides

2018 ◽  
Author(s):  
DeDe Kwun-Wai Man ◽  
Tokuwa Kanno ◽  
Giorgia Manzo ◽  
Brian D. Robertson ◽  
Jenny K.W. Lam ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Mycobacterium Smegmatis ◽  
Cell Envelope ◽  
Mycolic Acid ◽  
Magic Angle Spinning ◽  
Natural Resistance ◽  
Magic Angle ◽  
Trehalose Dimycolate ◽  
Angle Spinning ◽  
Mycobacterial Cell Wall

ABSTRACTThe mycobacterial cell wall affords natural resistance to antibiotics. Antimicrobial peptides (AMPs) modify the surface properties of mycobacteria and can act synergistically with antibiotics from differing classes. Here we investigate the response of Mycobacterium smegmatis to the presence of rifampicin or capreomycin, either alone or in combination with two synthetic, cationic, α-helical AMPs; distinguished by the presence (D-LAK120-HP13) or absence (D-LAK120-A) of a kink-inducing proline. Using a combination of high-resolution magic angle spinning (HR-MAS) NMR of bacteria, diphenylhexatriene (DPH) fluorescence anisotropy and laurdan emission spectroscopy we show that M. smegmatis responds to challenge with rifampicin or capreomycin by substantially altering its metabolism and, in particular, by remodelling the cell envelope. In NMR spectra of bacteria, reductions in intensity for mycolic acid lipid −(CH2)-, -CH3, R2CH-COOH, R2CH-OH and also -CH2-(CH==CH)- and -CH=CH- resonances were observed following challenge with rifampicin and capreomycin, while the latter also caused an increase in trehalose. These changes are consistent with a reduction of trehalose dimycolate and increase of trehalose monomycolate and are associated with an increase in rigidity of the mycolic acid layer observed following challenge by capreomycin but not rifampicin. Challenge with D-LAK120-A or D-LAK120-HP13 induced no or modest changes respectively in these metabolites and did not induce a significant increase in rigidity of the mycolic acid layer. Further, the response to rifampicin or capreomycin was significantly reduced when these were combined respectively with D-LAK120-HP13 and D-LAK120-A, suggesting a possible mechanism for the synergy of these combinations. The remodelling of the mycomembrane in M. smegmatis is therefore identified as an important countermeasure deployed against rifampicin or capreomycin, but this can be mitigated, and rifampicin or capreomycin efficacy potentiated, by combining with AMPs.

scholarly journals Control of Cell Wall Assembly by a Histone-Like Protein in Mycobacteria

2007 ◽  
Vol 189 (22) ◽  
pp. 8241-8249 ◽  
Author(s):  
Tomoya Katsube ◽  
Sohkichi Matsumoto ◽  
Masaki Takatsuka ◽  
Megumi Okuyama ◽  
Yuriko Ozeki ◽  
...  
Keyword(s):  
Cell Wall ◽  
Wall Structure ◽  
Regulation Mechanism ◽  
Mycolic Acids ◽  
Growth State ◽  
Cell Wall Assembly ◽  
Cell Wall Biogenesis ◽  
Covalently Linked ◽  
Mycobacterial Cell Wall ◽  
Wall Assembly

ABSTRACT Bacteria coordinate assembly of the cell wall as well as synthesis of cellular components depending on the growth state. The mycobacterial cell wall is dominated by mycolic acids covalently linked to sugars, such as trehalose and arabinose, and is critical for pathogenesis of mycobacteria. Transfer of mycolic acids to sugars is necessary for cell wall biogenesis and is mediated by mycolyltransferases, which have been previously identified as three antigen 85 (Ag85) complex proteins. However, the regulation mechanism which links cell wall biogenesis and the growth state has not been elucidated. Here we found that a histone-like protein has a dual concentration-dependent regulatory effect on mycolyltransferase functions of the Ag85 complex through direct binding to both the Ag85 complex and the substrate, trehalose-6-monomycolate, in the cell wall. A histone-like protein-deficient Mycobacterium smegmatis strain has an unusual crenellated cell wall structure and exhibits impaired cessation of glycolipid biosynthesis in the growth-retarded phase. Furthermore, we found that artificial alteration of the amount of the extracellular histone-like protein and the Ag85 complex changes the growth rate of mycobacteria, perhaps due to impaired down-regulation of glycolipid biosynthesis. Our results demonstrate novel regulation of cell wall assembly which has an impact on bacterial growth.

scholarly journals Structures of the mycobacterial membrane protein MmpL3 reveal its mechanism of lipid transport

PLoS Biology ◽  
2021 ◽  
Vol 19 (8) ◽  
pp. e3001370
Author(s):  
Chih-Chia Su ◽  
Philip A. Klenotic ◽  
Meng Cui ◽  
Meinan Lyu ◽  
Christopher E. Morgan ◽  
...  
Keyword(s):  
Cell Wall ◽  
Membrane Protein ◽  
Md Simulations ◽  
Mycolic Acid ◽  
Lipid Transport ◽  
X Ray Crystallography ◽  
Trehalose Dimycolate ◽  
Mycobacterial Cell ◽  
Mycobacterial Cell Wall ◽  
Trehalose Monomycolate

The mycobacterial membrane protein large 3 (MmpL3) transporter is essential and required for shuttling the lipid trehalose monomycolate (TMM), a precursor of mycolic acid (MA)-containing trehalose dimycolate (TDM) and mycolyl arabinogalactan peptidoglycan (mAGP), in Mycobacterium species, including Mycobacterium tuberculosis and Mycobacterium smegmatis. However, the mechanism that MmpL3 uses to facilitate the transport of fatty acids and lipidic elements to the mycobacterial cell wall remains elusive. Here, we report 7 structures of the M. smegmatis MmpL3 transporter in its unbound state and in complex with trehalose 6-decanoate (T6D) or TMM using single-particle cryo-electron microscopy (cryo-EM) and X-ray crystallography. Combined with calculated results from molecular dynamics (MD) and target MD simulations, we reveal a lipid transport mechanism that involves a coupled movement of the periplasmic domain and transmembrane helices of the MmpL3 transporter that facilitates the shuttling of lipids to the mycobacterial cell wall.

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