Dataset Information

The Pks13/FadD32 crosstalk for the biosynthesis of mycolic acids in Mycobacterium tuberculosis.

ABSTRACT: The last steps of the biosynthesis of mycolic acids, essential and specific lipids of Mycobacterium tuberculosis and related bacteria, are catalyzed by proteins encoded by the fadD32-pks13-accD4 cluster. Here, we produced and purified an active form of the Pks13 polyketide synthase, with a phosphopantetheinyl (P-pant) arm at both positions Ser-55 and Ser-1266 of its two acyl carrier protein (ACP) domains. Combination of liquid chromatography-tandem mass spectrometry of protein tryptic digests and radiolabeling experiments showed that, in vitro, the enzyme specifically loads long-chain 2-carboxyacyl-CoA substrates onto the P-pant arm of its C-terminal ACP domain via the acyltransferase domain. The acyl-AMPs produced by the FadD32 enzyme are specifically transferred onto the ketosynthase domain after binding to the P-pant moiety of the N-terminal ACP domain of Pks13 (N-ACP(Pks13)). Unexpectedly, however, the latter step requires the presence of active FadD32. Thus, the couple FadD32-(N-ACP(Pks13)) composes the initiation module of the mycolic condensation system. Pks13 ultimately condenses the two loaded fatty acyl chains to produce alpha-alkyl beta-ketoacids, the precursors of mycolic acids. The developed in vitro assay will constitute a strategic tool for antimycobacterial drug screening.

SUBMITTER: Gavalda S

PROVIDER: S-EPMC2740550 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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The Pks13/FadD32 crosstalk for the biosynthesis of mycolic acids in Mycobacterium tuberculosis.

Gavalda Sabine S Léger Mathieu M van der Rest Benoît B Stella Alexandre A Bardou Fabienne F Montrozier Henri H Chalut Christian C Burlet-Schiltz Odile O Marrakchi Hedia H Daffé Mamadou M Quémard Annaïk A

The Journal of biological chemistry 20090512 29

The last steps of the biosynthesis of mycolic acids, essential and specific lipids of Mycobacterium tuberculosis and related bacteria, are catalyzed by proteins encoded by the fadD32-pks13-accD4 cluster. Here, we produced and purified an active form of the Pks13 polyketide synthase, with a phosphopantetheinyl (P-pant) arm at both positions Ser-55 and Ser-1266 of its two acyl carrier protein (ACP) domains. Combination of liquid chromatography-tandem mass spectrometry of protein tryptic digests an ...[more]

PMID: 19436070

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Project description:Background: Among the nineteen polyketide synthases encoded by the genome of Mycobacterium tuberculosis, Pks13 was identified as the condensase required for the final condensation step of two long acyl chains. This leads to mycolic acids, which are essential components of the cell envelope of Corynebacterineae species. The single polypeptide chain of Pks13 comprises five catalytic domains, including two functional acyl carrier protein domains, separated by linkers comprising up to ca. 200 amino acid residues. In many aspects, Pks13 is an atypical polyketide synthase. It has been validated as a promising druggable target and its structure is badly needed to speed up drug discovery to fight against tuberculosis. Results: We report here a quasi-atomic model of Pks13 obtained using small angle X-ray scattering of the entire protein and various molecular subspecies combined with known high-resolution structures of Pks13 domains or structural homologues. In addition, the structural changes induced by the loading of a substrate analogue have been challenged. As a comparison, the low-resolution structures of two other mycobacterial polyketide synthases, Mas and PpsA from Mycobacterium bovis BCG, are also presented. This study highlights an identical and elongated structure of the apo and holo forms at the resolution probed. Catalytic domains are segregated into two parts, which correspond to the condensation reaction per se and to the release of the product, a pivot for the enzyme flexibility being at the interface. The two acyl carrier protein domains are found at opposite sides of the ketosynthase domain and display distinct characteristics in terms of flexibility. Apo-Pks13 is in our conditions in a monomeric state, but loading of a substrate analogue push the enzyme towards the functional dimeric state. Conclusions: The Pks13 model provides the first structural information on the molecular mechanism of this complex enzyme and open up new perspectives to develop inhibitors that target the interactions with its enzymatic partners or between catalytic domains within Pks13 itself.

Dataset Information

The Pks13/FadD32 crosstalk for the biosynthesis of mycolic acids in Mycobacterium tuberculosis.

Publications

The Pks13/FadD32 crosstalk for the biosynthesis of mycolic acids in Mycobacterium tuberculosis.

Similar Datasets

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