Synthesis of trehalose dimycolate (cord factor) by a cell-free system of Mycobacteriumsmegmatis

Kilburn, James O.; Takayama, K.; Armstrong, Emma Lee

doi:10.1016/0006-291x(82)91841-1

Cited by 27 publications

(21 citation statements)

References 13 publications

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“…A putative transfer of newly synthesized mycolates (unsaturated and 0x0) from their extractable forms towards their wall-linked forms was described in M . tuberculosis H37 Ra [27,28]. In our case there was no decrease with time of the labelling in the extractable forms but experiments only lasted 15 min and the decrease may appear later.…”

Section: Metabolic Filiation Between Mycolate Typescontrasting

confidence: 49%

Mycolic acid metabolic filiation and location in Mycobacterium aurum and Mycobacterium phlei

Lacave

Lanéelle

Daffé

et al. 1989

European Journal of Biochemistry

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Synchronous cultures of Mycobacterium aurum were used to prove a close relationship between cellular division and active synthesis of mycolic acids (characteristic long-chain 3-hydroxyacids, branched at position 2), confirming previous proposals.Mycolic acid biosynthesis was studied in two species (Mycobacterium phlei and M. aurum) each producing three types of mycolic acids : di-unsatured mycolates, oxomycolates and wax-ester mycolates (ester of dicarboxymycolic acid and 2-icosanol or 2-octadecanol). It was shown that unsaturated mycolates and oxomycolic acids were not directly related, whereas a metabolic filiation was confirmed between oxomycolate and wax ester mycolate: the latter derived from the former by a Baeyer-Villiger oxidation step, as has been proposed on the basis of structural considerations.By observing the labelling of the different mycolate pools in the cell, i. e. the organic-solvent-extractable fraction (essentially containing esters of trehalose and of glycerol) and the cell residue (assumed to be the cellwall polymers), it was clear that oxomycolates and unsaturated mycolates appeared first in the extractable lipids, then in the wall-linked mycolates while wax-ester mycolates appeared first as wall-linked derivatives. Thus, it is proposed that mycolates could follow separate routes involving differently located enzymes to reach their complex forms either in extractable lipids or in the wall-linked arabino-galactan.The biosynthetic routes to mycolic acids [characteristic very long-chain ( c 6 0 branched at position 2, 3-hydroxy acids] of Mycobacteria are still obscure, in spite of the interest of these fatty acids as taxonomic markers [l, 21 and as one of the possible targets of some widely used antituberculosis drugs Most studies on the biogenesis of these wall-located fatty acids [R-CHOH-CH(R')-COOH] concern unsaturated mycolic acids in which R is di-unsaturated Mycobacterium species synthesize other types of mycolic acids in which R contains oxygenated functions (ketone, epoxy, methoxy, ester) and is only mono-unsaturated. Introduction of the oxygenated functional groups poses several unsolved questions. The discussion about an eventual filiation between unsaturated and oxygenated mycolic acids has lasted several decades [9] and has been the subject of extensive speculation [7]. In 1965, Etemadi [lo] proposed the hypothetical pathway shown in Scheme 1 : wax-ester mycolates (i.e. a dicarboxymycolate esterified on its w-carboxyl by a methylcarbinol) [l 11 and methoxymycolates should derive from a common oxomycolate precursor by either a Baeyer-Villiger oxidation or a methylation step, respectively [7]. More recently, the Baeyer-Villiger oxidation was supported by Yano et al. [12], who showed that after incubation in the presence of "0 and degradation of wax-ester mycolate into dicarboxy acid and alcohol (Scheme l), only the oxygen atom of the alcohol (2-octadecanol or 2-icosanol according to the species) was labelled. But this experiment did not bring any evidence that oxidation takes ...

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Section: Metabolic Filiation Between Mycolate Typescontrasting

confidence: 49%

Mycolic acid metabolic filiation and location in Mycobacterium aurum and Mycobacterium phlei

Lacave

Lanéelle

Daffé

et al. 1989

European Journal of Biochemistry

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“…This would be a requirement for normal growth of M. tuberculosis. It prevents the conversion of TMM to TDM inside the cell by the ubiquitously present Ag85/Fbp (47,89). Such a reaction is to be avoided, since it would effectively consume most of the TMM synthesized internally and make it unavailable for transport outside the cell.…”

Section: Processing Of Newly Synthesized Mycolic Acidsmentioning

confidence: 99%

Pathway to Synthesis and Processing of Mycolic Acids in Mycobacterium tuberculosis

2005

Self Cite

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Mycobacterium tuberculosis is known to synthesize α-, methoxy-, and keto-mycolic acids. We propose a detailed pathway to the biosynthesis of all mycolic acids in M. tuberculosis. Fatty acid synthetase I provides C20-S-coenzyme A to the fatty acid synthetase II system (FAS-IIA). Modules of FAS-IIA and FAS-IIB introduce cis unsaturation at two locations on a growing meroacid chain to yield three different forms of cis,cis-diunsaturated fatty acids (intermediates to α-, methoxy-, and keto-meroacids). These are methylated, and the mature meroacids and carboxylated C26-S-acyl carrier protein enter into the final Claisen-type condensation with polyketide synthase-13 (Pks13) to yield mycolyl-S-Pks13. We list candidate genes in the genome encoding the proposed dehydrase and isomerase in the FAS-IIA and FAS-IIB modules. We propose that the processing of mycolic acids begins by transfer of mycolic acids from mycolyl-S-Pks13 to d-mannopyranosyl-1-phosphoheptaprenol to yield 6-O-mycolyl-β-d-mannopyranosyl-1-phosphoheptaprenol and then to trehalose 6-phosphate to yield phosphorylated trehalose monomycolate (TMM-P). Phosphatase releases the phosphate group to yield TMM, which is immediately transported outside the cell by the ABC transporter. Antigen 85 then catalyzes the transfer of a mycolyl group from TMM to the cell wall arabinogalactan and to other TMMs to produce arabinogalactan-mycolate and trehalose dimycolate, respectively. We list candidate genes in the genome that encode the proposed mycolyltransferases I and II, phosphatase, and ABC transporter. The enzymes within this total pathway are targets for new drug discovery

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“…This assay utilized an ESI-MS techniques to directly monitor trehalose and TDM formation [144]. Prior to the MS-based assay, Ag85 inhibition assays were monitoring enzyme coupling or generic mycolyl transferase activity [23, 27, 145]. The mechanism-based inhibitor probe ( 107 ) was able to reduce enzymatic activity by ∼93% at 150 μM [144] (Figure 21).…”

Section: New Inhibitors Of the Mycolic Acid Biosynthetic Pathwaymentioning

confidence: 99%

New Approaches to Target the Mycolic Acid Biosynthesis Pathway for the Development of Tuberculosis Therapeutics

North¹,

Jackson²,

Lee³

2013

CPD

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Mycolic acids are the major lipid component of the unique mycobacterial cell wall responsible for the protection of the tuberculosis bacilli from many outside threats. Mycolic acids are synthesized in the cytoplasm and transported to the outer membrane as trehalose-containing glycolipids before being esterified to the arabinogalactan portion of the cell wall and outer membrane glycolipids. The large size of these unique fatty acids is a result of a huge metabolic investment that has been evolutionarily conserved, indicating the importance of these lipids to the mycobacterial cellular survival. There are many key enzymes involved in the mycolic acid biosynthetic pathway, including fatty acid synthesis (KasA, KasB, MabA, InhA, HadABC), mycolic acid modifying enzymes (SAM-dependent methyltransferases, aNAT), fatty acid activating and condensing enzymes (FadD32, Acc, Pks13), transporters (MmpL3) and tranferases (Antigen 85A-C) all of which are excellent potential drug targets. Not surprisingly, in recent years many new compounds have been reported to inhibit specific portions of this pathway, discovered through both phenotypic screening and target enzyme screening. In this review, we analyze the new and emerging inhibitors of this pathway discovered in the post-genomic era of tuberculosis drug discovery, several of which show great promise as selective tuberculosis therapeutics.

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Synthesis of trehalose dimycolate (cord factor) by a cell-free system of Mycobacteriumsmegmatis

Cited by 27 publications

References 13 publications

Mycolic acid metabolic filiation and location in Mycobacterium aurum and Mycobacterium phlei

Mycolic acid metabolic filiation and location in Mycobacterium aurum and Mycobacterium phlei

Pathway to Synthesis and Processing of Mycolic Acids in Mycobacterium tuberculosis

New Approaches to Target the Mycolic Acid Biosynthesis Pathway for the Development of Tuberculosis Therapeutics

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