Premium
Delineation of the roles of FadD22, FadD26 and FadD29 in the biosynthesis of phthiocerol dimycocerosates and related compounds in Mycobacterium tuberculosis
Author(s) -
Siméone Roxane,
Léger Mathieu,
Constant Patricia,
Malaga Wladimir,
Marrakchi Hedia,
Daffé Mamadou,
Guilhot Christophe,
Chalut Christian
Publication year - 2010
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2010.07688.x
Subject(s) - biosynthesis , biology , mycobacterium tuberculosis , biochemistry , dna ligase , gene , polyketide , orfs , mutant , gene cluster , mycobacterium , glycolipid , complementation , genetics , open reading frame , tuberculosis , bacteria , peptide sequence , medicine , pathology
Phthiocerol and phthiodiolone dimycocerosates (DIMs) and phenolic glycolipids (PGLs) are complex lipids located at the cell surface of Mycobacterium tuberculosis that play a key role in the pathogenicity of tuberculosis. Most of the genes involved in the biosynthesis of these compounds are clustered on a region of the M. tuberculosis chromosome, the so‐called DIM + PGL locus. Among these genes, four ORFs encode FadD proteins, which activate and transfer biosynthetic intermediates onto various polyketide synthases that catalyze the formation of these lipids. In this study, we investigated the roles of FadD22, FadD26 and FadD29 in the biosynthesis of DIMs and related compounds. Biochemical characterization of the lipids produced by a spontaneous Mycobacterium bovis BCG mutant harboring a large deletion within fadD26 revealed that FadD26 is required for the production of DIMs but not of PGLs. Additionally, using allelic exchange recombination, we generated an unmarked M. tuberculosis mutant containing a deletion within fadD29 . Biochemical analyses of this strain revealed that, like fadD22 , this gene encodes a protein that is specifically involved in the biosynthesis of PGLs, indicating that both FadD22 and FadD29 are responsible for one particular reaction in the PGL biosynthetic pathway. These findings were also supported by in vitro enzymatic studies showing that these enzymes have different properties, FadD22 displaying a p ‐hydroxybenzoyl‐AMP ligase activity, and FadD29 a fatty acyl‐AMP ligase activity. Altogether, these data allowed us to precisely define the functions fulfilled by the various FadD proteins encoded by the DIM + PGL cluster.