Administration of a donor of nitric oxide inhibits mglA expression of intracellular Francisella tularensis and counteracts phagosomal escape and subversion of TNF-α secretion
2011 (English)In: Journal of Medical Microbiology, ISSN 0022-2615, E-ISSN 1473-5644, Vol. 30, no 11, 1570-1583 p.Article in journal (Refereed) Published
Francisella tularensis is a highly virulent intracellular bacterium capable of rapid multiplication in phagocytic cells. Previous studies have revealed that activation of F. tularensis-infected macrophages leads to control of infection and reactive nitrogen and oxygen species make important contributions to the bacterial killing. We investigated the effects of adding S-nitroso-acetyl-penicillamine (SNAP), which generates nitric oxide or 3-morpholinosydnonimine hydrochloride (SIN-1), which indirectly leads to formation of peroxynitrite, to J774 murine macrophage-like cell cultures infected with F. tularensis LVS. Addition of SNAP led to significantly increased colocalization between LAMP-1 and bacteria, indicating containment of F. tularensis in the phagosome within 2 h, although no killing occurred within 4 h. A specific inhibitory effect on bacterial transcription was observed since the gene encoding the global regulator MglA was inhibited 50- to 100-fold. F. tularensis-infected J774 cells are incapable of secreting TNF-alpha in response to Escherichia coli LPS but addition of SNAP almost completely reversed the suppression. Similarly, infection with an MglA mutant did not inhibit LPS-induced TNF-alpha secretion of J774 cells. Strong staining for nitrotyrosine was observed in SNAP-treated bacteria and mass spectrometry identified nitration of two ribosomal 50S proteins, a CBS domain pair protein, and bacterioferritin. The results demonstrate that addition of SNAP initially did not affect the viability of intracellular F. tularensis LVS but led to containment of the bacteria in the phagosome. Moreover, the treatment resulted in nitration of several F. tularensis proteins.
Place, publisher, year, edition, pages
2011. Vol. 30, no 11, 1570-1583 p.
Francisella tularensis, macrophage activation, TNF-α, Igl proteins, nitric oxide
Microbiology in the medical area
Research subject Microbiology
IdentifiersURN: urn:nbn:se:umu:diva-45864DOI: 10.1099/jmm.0.032870-0ISI: 000296547900002PubMedID: 21700740OAI: oai:DiVA.org:umu-45864DiVA: diva2:435620