PapA1 and PapA2 are acyltransferases essential for the biosynthesis of the Mycobacterium tuberculosis virulence factor Sulfolipid-1

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 27; pp. 11221 - 11226
• Main Authors: Kumar, Pawan, Schelle, Michael W, Jain, Madhulika, Lin, Fiona L, Petzold, Christopher J, Leavell, Michael D, Leary, Julie A, Cox, Jeffery S, Bertozzi, Carolyn R
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.07.2007; National Acad Sciences
• Subjects: Acylation; Acyltransferases - genetics; Acyltransferases - isolation & purification; Acyltransferases - physiology; Animals; Bacteria; Bacterial Proteins - biosynthesis; Bacterial Proteins - isolation & purification; Bacterial Proteins - physiology; Biochemistry; Biological Sciences; Biosynthesis; Enzymes; Glycolipids - biosynthesis; Infections; Lipids; Mice; Multigene Family; Mycobacterium tuberculosis; Mycobacterium tuberculosis - enzymology; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - pathogenicity; Polyketides; Rodents; Trehalose - analogs & derivatives; Trehalose - metabolism; Tuberculosis; Tuberculosis - enzymology; Tuberculosis - microbiology; Virulence; Virulence Factors - biosynthesis
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0611649104

Mycobacterium tuberculosis produces numerous exotic lipids that have been implicated as virulence determinants. One such glycolipid, Sulfolipid-1 (SL-1), consists of a trehalose-2-sulfate (T2S) core acylated with four lipid moieties. A diacylated intermediate in SL-1 biosynthesis, SL₁₂₇₈, has been shown to activate the adaptive immune response in human patients. Although several proteins involved in SL-1 biosynthesis have been identified, the enzymes that acylate the T2S core to form SL₁₂₇₈ and SL-1, and the biosynthetic order of these acylation reactions, are unknown. Here we demonstrate that PapA2 and PapA1 are responsible for the sequential acylation of T2S to form SL₁₂₇₈ and are essential for SL-1 biosynthesis. In vitro, recombinant PapA2 converts T2S to 2'-palmitoyl T2S, and PapA1 further elaborates this newly identified SL-1 intermediate to an analog of SL₁₂₇₈. Disruption of papA2 and papA1 in M. tuberculosis confirmed their essential role in SL-1 biosynthesis and their order of action. Finally, the ΔpapA2 and ΔpapA1 mutants were screened for virulence defects in a mouse model of infection. The loss of SL-1 (and SL₁₂₇₈) did not appear to affect bacterial replication or trafficking, suggesting that the functions of SL-1 are specific to human infection.