Infect Immun. 2011 Oct 17. [Epub ahead of print]
A patatin-like protein protects Toxoplasma gondii from degradation in a nitric oxide dependent manner
Tobin CM, Knoll LJ
SourceDepartment of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706.
Toxoplasma gondii is an obligate intracellular parasite that uses immune cells to disseminate throughout its host. T. gondii can persist and even slowly replicate in activated host macrophages by reducing the antimicrobial effects of molecules such as nitric oxide (NO). A T. gondii patatin-like protein called TgPL1 was previously shown to be important for survival in activated macrophages. Here we show that a T. gondii mutant with a deletion of the TgPL1 gene (ΔTgPL1) is degraded in activated macrophages. This degradation phenotype is abolished by the removal of NO by the use of an iNOS inhibitor or iNOS deficient macrophages. Exogenous addition of NO to macrophages results in reduced parasite growth, but not degradation of ΔTgPL1 parasites. These results suggest that NO is necessary but not sufficient for the degradation of ΔTgPL1 parasites in activated macrophages. While some patatin-like proteins have phospolipase A(2) (PLA(2)) activity, recombinant TgPL1 purified from E. coli does not have phospholipase activity. This result was not surprising as TgPL1 contains a G to S change at the predicted catalytic serine residue. An epitope tagged version of TgPL1 partially co-localizing with a dense granule protein in the parasitophorous vacuole space. These results may suggest that TgPL1 moves to the parasitophorous vacuole to protect parasites from nitric oxide by an undetermined mechanism.
PMID:22006568[PubMed - as supplied by publisher]