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Genetic rescue of a Toxoplasma gondii conditional cell cycle mutant
Author(s) -
White Michael W.,
Jerome Maria E.,
Vaishnava Shipra,
Guerini Michael,
Behnke Michael,
Striepen Boris
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04471.x
Subject(s) - biology , centrosome , mitosis , mutant , microbiology and biotechnology , cell cycle , genetics , toxoplasma gondii , cell division , gene , cell , antibody
Summary Growth rate is a major pathogenesis factor in the parasite Toxoplasma gondii ; however, how cell division is controlled in this protozoan is poorly understood. Herein, we show that centrosomal duplication is an indicator of S phase entry while centrosome migration marks mitotic entry. Using the pattern of centrosomal replication, we confirmed that mutant ts 11C9 undergoes a bimodal cell cycle arrest that is characterized by two subpopulations containing either single or duplicated centrosomes which correlate with the bipartite genome distribution observed at the non‐permissive temperature. Genetic rescue of ts 11C9 was performed using a parental RH strain cDNA library, and the cDNA responsible for conferring temperature resistance (growth at 40°C) was recovered by recombination cloning. A single T. gondii gene encoding the protein homologue of XPMC2 was responsible for genetic rescue of the temperature‐sensitive defect in ts 11C9 parasites. This protein is a known suppressor of mitotic defects, and in tachyzoites, TgXPMC2–YFP localized to the parasite nucleus and nucleolus which is consistent with the expected subcellular localization of critical mitotic factors. Altogether, these results demonstrate that ts 11C9 is a conditional mitotic mutant containing a single defect which influences two distinct control points in the T. gondii tachyzoite cell cycle.