Changes of the phagosomal elemental concentrations by Mycobacterium tuberculosis Mramp.
Pathogenic mycobacteria survive within phagosomes which are thought to represent a nutrient-restricted environment. Divalent cation transporters of the Nramp family in phagosomes and mycobacteria (Mramp) may compete for metals that are crucial for bacterial survival. The elemental concentrations in phagosomes of macrophages infected with wild-type Mycobacterium tuberculosis (M. tuberculosis strain H37Rv) and a M. tuberculosis Mramp knockout mutant (Mramp-KO), derived from a clinical isolate isogenic to the strain MT103, were compared. Time points of 1 and 24 h after infection of mouse peritoneal macrophages (bcg(S)) were compared in both cases. Increased concentrations of P, Ni and Zn and reduced Cl concentration in Mramp-KO after 1 h of infection were observed, compared to M. tuberculosis vacuoles. After 24 h of infection, significant differences in the P, Cl and Zn concentrations were still present. The Mramp-KO phagosome showed a significant increase of P, Ca, Mn, Fe and Zn concentrations between 1 and 24 h after infection, while the concentrations of K and Ni decreased. In the M. tuberculosis vacuole, the Fe concentration showed a similar increase, while the Cl concentration decreased. The fact that the concentration of several divalent cations increased in the Mramp-KO strain suggests that Mramp may have no impact on the import of these divalent cations into the mycobacterium, but may function as a cation efflux pump. The concordant increase of Fe concentrations within M. tuberculosis, as well as within the Mramp-KO vacuoles, implies that Mramp, in contrast to siderophores, might not be important for the attraction of Fe and its retention in phagosomes of unstimulated macrophages.
Wagner
Dirk
D
Division of Infectious Diseases, Department of Internal Medicine, University of Freiburg, Hugstetter Str 55, 79106 Freiburg, Germany.
Maser
Jörg
J
Experimental Facilities, Argonne National Laboratory, Argonne, IL, USA.
Moric
Ivana
I
Experimental Facilities, Argonne National Laboratory, Argonne, IL, USA.
Boechat
Neio
N
Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France.
Vogt
Stefan
S
Experimental Facilities, Argonne National Laboratory, Argonne, IL, USA.
Gicquel
Brigitte
B
Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France.
Lai
Barry
B
Experimental Facilities, Argonne National Laboratory, Argonne, IL, USA.
Reyrat
Jean-Marc
JM
Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France.
Bermudez
Luiz
L
Department of Microbiology, College of Science, Oregon State University, Corvallis, OR, USA.|Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA.
D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism*; D017353:Gene Deletion; D006801:Humans; D017136:Ion Transport; D017737:Macrophages, Peritoneal / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism*
D027682:Cation Transport Proteins; D002413:Cations, Divalent