The role of MmpL8 in sulfatide biogenesis and virulence of Mycobacterium tuberculosis.
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-alpha,alpha'-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.
Tuberculosis Research Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA.
Pilar
P
Domenech
Michael B
MB
Reed
Cynthia S
CS
Dowd
Claudia
C
Manca
Gilla
G
Kaplan
Clifton E
CE
Barry
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008055:Lipids / Q000096:biosynthesis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D009169:Mycobacterium tuberculosis / Q000378:metabolism* / Q000472:pathogenicity*; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D013433:Sulfoglycosphingolipids / Q000378:metabolism*; D014774:Virulence
D001426:Bacterial Proteins; D008055:Lipids; D008565:Membrane Proteins; C487808:MmpL8 protein, Mycobacterium tuberculosis; D011994:Recombinant Proteins; D013433:Sulfoglycosphingolipids; C015518:sulfolipids