Analysis of stress- and host cell-induced expression of the Mycobacterium tuberculosis inorganic pyrophosphatase.
BACKGROUND
The gene encoding the inorganic pyrophosphatase (PPase) of the intracellular pathogen Legionella pneumophila is induced during intracellular infection, but is constitutively expressed in Escherichia coli. The causative agent of tuberculosis, Mycobacterium tuberculosis, contains a well conserved copy of PPase. We sought to determine if expression of the M. tuberculosis PPase is regulated by the intracellular environment.


RESULTS
A strain of Mycobacterium bovis bacille Calmette-Guérin (BCG) was constructed in which the Aequoria victoria green fluorescent protein (GFP) is controlled by the promoter of the M. tuberculosis ppa gene. After prolonged exposure of the recombinant BCG strain within murine bone-marrow-derived macrophages, there was no observed increased activity of the ppa promoter. Furthermore, there was no change in promoter activity after exposure to various stress stimuli such as reduced pH, osmotic shock, nutrient limitation or oxidative stress.


CONCLUSIONS
These results suggest that macrophage induction of ppa is not a general phenomenon among intracellular pathogens.
Triccas
J A
JA
Unité de Génétique Mycobactérienne, Institut Pasteur, 25 rue du Dr, Roux, 75724 Paris Cedex 15, France. J.Triccas@centenary.usyd.edu.au
Gicquel
B
B
D000818:Animals; D004790:Enzyme Induction; D015870:Gene Expression / Q000502:physiology*; D043564:Inorganic Pyrophosphatase; D008264:Macrophages / Q000382:microbiology / Q000502:physiology*; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D009997:Osmotic Pressure; D018384:Oxidative Stress / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000502:physiology; D011755:Pyrophosphatases / Q000096:biosynthesis* / Q000235:genetics
D011755:Pyrophosphatases; D043564:Inorganic Pyrophosphatase