Molecular profiling of Mycobacterium tuberculosis identifies tuberculosinyl nucleoside products of the virulence-associated enzyme Rv3378c.
Proc Natl Acad Sci U S A
; 111(8): 2978-83, 2014 Feb 25.
Article
en En
| MEDLINE
| ID: mdl-24516143
ABSTRACT
To identify lipids with roles in tuberculosis disease, we systematically compared the lipid content of virulent Mycobacterium tuberculosis with the attenuated vaccine strain Mycobacterium bovis bacillus Calmette-Guérin. Comparative lipidomics analysis identified more than 1,000 molecular differences, including a previously unknown, Mycobacterium tuberculosis-specific lipid that is composed of a diterpene unit linked to adenosine. We established the complete structure of the natural product as 1-tuberculosinyladenosine (1-TbAd) using mass spectrometry and NMR spectroscopy. A screen for 1-TbAd mutants, complementation studies, and gene transfer identified Rv3378c as necessary for 1-TbAd biosynthesis. Whereas Rv3378c was previously thought to function as a phosphatase, these studies establish its role as a tuberculosinyl transferase and suggest a revised biosynthetic pathway for the sequential action of Rv3377c-Rv3378c. In agreement with this model, recombinant Rv3378c protein produced 1-TbAd, and its crystal structure revealed a cis-prenyl transferase fold with hydrophobic residues for isoprenoid binding and a second binding pocket suitable for the nucleoside substrate. The dual-substrate pocket distinguishes Rv3378c from classical cis-prenyl transferases, providing a unique model for the prenylation of diverse metabolites. Terpene nucleosides are rare in nature, and 1-TbAd is known only in Mycobacterium tuberculosis. Thus, this intersection of nucleoside and terpene pathways likely arose late in the evolution of the Mycobacterium tuberculosis complex; 1-TbAd serves as an abundant chemical marker of Mycobacterium tuberculosis, and the extracellular export of this amphipathic molecule likely accounts for the known virulence-promoting effects of the Rv3378c enzyme.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Conformación Proteica
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Proteínas Bacterianas
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Modelos Moleculares
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Transferasas Alquil y Aril
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Lípidos
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Mycobacterium tuberculosis
Tipo de estudio:
Risk_factors_studies
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2014
Tipo del documento:
Article