Disruption of the gene homologous to mammalian Nramp1 in Mycobacterium tuberculosis does not affect virulence in mice.
Natural-resistance-associated macrophage protein 1 (Nramp1) is a divalent cation transporter belonging to a family of transporter proteins highly conserved in eukaryotes and prokaryotes. Mammalian and bacterial transporters may compete for essential metal ions during mycobacterial infections. The mycobacterial Nramp homolog may therefore be involved in Mycobacterium tuberculosis virulence. Here, we investigated this possibility by inactivating the M. tuberculosis Nramp1 gene (Mramp) by allelic exchange mutagenesis. Disruption of Mramp did not affect the extracellular growth of bacteria under standard conditions. However, the Mramp mutation was associated with growth impairment under conditions of limited iron availability. The Mramp mutant displayed no impairment of growth or survival in macrophages derived from mouse bone marrow or in Nramp1(+/+) and Nramp1(-/-) congenic murine macrophage cell lines. Following intravenous challenge in BALB/c mice, counts of parental and Mramp mutant strains were similar in the lungs and spleens of the animals at all time points studied. These results indicate that Mramp does not contribute to the virulence of M. tuberculosis in mice.
Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France.
Neio
N
Boechat
Béatrice
B
Lagier-Roger
Stéphanie
S
Petit
Yann
Y
Bordat
Jean
J
Rauzier
Allan J
AJ
Hance
Brigitte
B
Gicquel
Jean-Marc
JM
Reyrat
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology / Q000382:microbiology; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D018390:Gene Targeting; D007501:Iron / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D016296:Mutagenesis; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D014774:Virulence; D000099173:Natural Resistance-associated Macrophage Protein 1
D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D003470:Culture Media; D007501:Iron; D000099173:Natural Resistance-associated Macrophage Protein 1