Date of Completion


Document Type

Honors College Thesis


Department of Microbiology and Molecular Genetics

Thesis Type

Honors College

First Advisor

Dr. Gary E. Ward

Second Advisor

Anne Kelsen


Toxoplasma gondii, Actin, Motility Assay


Toxoplasma gondii, an obligate intracellular apicomplexan parasite, utilizes gliding motility for active penetration and proactive egress from host cells. Gliding motility is made possible in apicomplexan parasites by use of the myosin motor complex, which is an actin-activated molecular motor. Toxoplasma actin is encoded by the single copy ACT1 gene which is transcribed and translated into a single actin isoform and is inherently unstable in the filamentous form. In T. gondii, globular actin polymerizes to filamentous actin and is then driven rearward by the myosin motor during gliding motility. Prior research has shown differences between Apicomplexan and mammalian actin and myosin. The in vitro motility assay is used to study the Toxoplasma myosin motor complex, and chicken skeletal muscle actin is used in place of Toxoplasma actin. Here, recombinant Toxoplasma actin is expressed, purified, and polymerized in preparation for labeling and use in the in vitro motility assay. Confirmation of Toxoplasma actin expression was achieved by sequencing baculovirus encoding recombinant Toxoplasma actin and western blot analysis. Purification was achieved via nickel affinity chromatography, followed by cycles of polymerization and depolymerization. Preparing stabilized and labeled actin filaments allows for the comparison of the speeds Toxoplasma myosin moves Toxoplasma actin versus mammalian actin.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.