To study the role of MmpL8-mediated lipid transport in sulfatide biogenesis, we insertionally inactivated the mmpL8 gene in Mycobacterium tuberculosis. Characterization of this strain showed that the synthesis of mature sulfolipid SL-1 was interrupted and that a more polar sulfated molecule, termed SL-N, accumulated within the cell. Purification of SL-N and structural analysis identified this molecule as a family of 2,3-diacyl-α,α'-D-trehalose-2'-sulfates. This structure suggests that transport and biogenesis of SL-1 are coupled and that the final step in sulfatide biosynthesis may be the extra-cellular esterification of two trehalose 6-positions with hydroxyphthioceranic acids. To assess the effect of the loss of this anionic surface lipid on virulence, we infected mice via aerosol with the MmpL8 mutant and found that, although initial replication rates and containment levels were identical, compared with the wild type, a significant attenuation of the MmpL8 mutant strain in time-to-death was observed. Early in infection, differential expression of cytokines and cytokine receptors revealed that the mutant strain less efficiently suppresses key indicators of a Th1-type immune response, suggesting an immunomodulatory role for sulfatides in the pathogenesis of tuberculosis.
biosynthesis, Bacterial Proteins, Gene Expression Regulation, metabolism, virulence, Restriction Mapping, lipids, Membrane Proteins, Mycobacterium tuberculosis, Sulfoglycosphingolipids
NCBI PubMed ID: 15001577Publication DOI: 10.1074/jbc.M400324200Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: cbarry@niaid.nih.gov
Institutions: Tuberculosis Research Section, NIAID, National Institutes of Health, Rockville, Maryland 20852 and the §Public Health Research Institute, Newark, New Jersey 07103, Tuberculosis Research Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA
Methods: NMR-2D, ESI-MS
Found