Inhibition ofToxoplasma gondiiReplication by Dinitroaniline Herbicides

Dinitroanilines Bind α-Tubulin to Disrupt Microtubules

“…There are two populations of microtubules in the invasive stages of apicomplexan parasites: subpellicular microtubules and spindle microtubules (Morrissette and Sibley, 2002a,b). Subpellicular microtubules are nondynamic; they maintain both apical polarity and the characteristic crescent shape of the parasite by interacting with the pellicle (Morrissette et al, 1997 are refractory to the effects of microtubule-disrupting drugs, during intracellular growth parasite microtubules are dynamic and are highly sensitive to disruption (Stokkermans et al, 1996). In this work, we demonstrate that Toxoplasma resistance to oryzalin is associated with point mutations to ␣-tubulin.…”

“…Dinitroanilines (oryzalin, ethafluralin, and trifluralin) disrupt the microtubules of plants, ranging from the single-celled alga Chlamydomonas reinhardtii to higher plants such as the monocot Eleusine indica (James et al, 1993;Anthony et al, 1998;Zeng and Baird, 1999). Dinitroanilines also disrupt the microtubules of protozoa, including both free-living species such as Tetrahymena and protozoan parasites such as Trypanosoma spp., Leishmania spp., Entamoeba spp., Plasmodium falciparum, Cryptosporidium parvum, and Toxoplasma gondii (Chan and Fong, 1990;Chan et al, 1991;Gu et al, 1995;Edlind et al, 1996;Stokkermans et al, 1996;Armson et al, 1999; Makioka et al, 2000a,b;Traub-Cseko et al, 2001). Remarkably, the activity of dinitroanilines is restricted to plants and protozoa; these compounds are ineffective against vertebrate or fungal microtubules (Chan and Fong, 1990;Hugdahl and Morejohn, 1993;Murthy et al, 1994;Edlind et al, 1996).…”

“…Both populations are critically important to parasite survival and replication. Although extracellular parasites are refractory to the effects of microtubule-disrupting drugs, during intracellular growth parasite microtubules are dynamic and are highly sensitive to disruption (Stokkermans et al, 1996).…”

“…It is therefore ideally suited for genetic analysis of recessive mutations that would be masked in a diploid organism, particularly one with redundant gene family members. These genetic qualities allowed the isolation of a large number of tubulin mutations that are partially recessive to wild-type tubulin.It is well established that dinitroanilines selectively inhibit the microtubules of plants and protozoa and do not act on fungal or vertebrate tubulins (Chan and Fong, 1990;Chan et al, 1991;James et al, 1993;Gu et al, 1995;Edlind et al, 1996;Stokkermans et al, 1996;Anthony et al, 1998Armson et al, 1999;Zeng and Baird, 1999; Makioka et al, 2000a,b;Traub-Cseko et al, 2001). Dinitroaniline disruption of plant microtubules has been exploited to develop these compounds as components of a variety of preemergence herbicides.…”

Differential Localization of Alternatively Spliced Hypoxanthine-Xanthine-Guanine Phosphoribosyltransferase Isoforms in Toxoplasma gondii

“…Antisense primer 5Ј-GGGCTCAATACGGCCgtcgacCTTGCCGTAGTC-3Ј was used to introduce a SalI site in HXGPRT expression vectors at amino acids 12 and 13 of HXGPRT-I (in pdhfrHXGPRT-I) and 61 and 62 of HXGPRT-II (in pdhfrHXGPRT-II and pdhfrHXGPRT-II-C (23)(24)(25)S. Antisense primer 5Ј-CCAGTGATTTTTTTctcgagTTTAGATCTGAC-3Ј was used to introduce an XhoI site at CAT translational start in vector pdhfrCAT.…”