From Tg O/GABA-AT, GABA, and T-263 Mutant to Conception of Toxoplasma

Joseph Lykins; Matthew J Moschitto; Ying Zhou; Ekaterina V Filippova; Hoang V Le; Tadakimi Tomita; Barbara A Fox; David J Bzik; Chunlei Su; Seesandra V Rajagopala; Kristin Flores; Furio Spano; Stuart Woods; Craig W Roberts; Cong Hua; Kamal El Bissati; Kelsey M Wheeler; Sarah Dovgin; Stephen P Muench; Martin McPhillie; Colin W G Fishwick; Wayne F Anderson; Patricia J Lee; Mark Hickman; Louis M Weiss; Jitender P Dubey; Hernan A Lorenzi; Richard B Silverman; Rima L McLeod

doi:10.1016/j.isci.2023.108477

From Tg O/GABA-AT, GABA, and T-263 Mutant to Conception of Toxoplasma

iScience. 2023 Nov 16;27(1):108477. doi: 10.1016/j.isci.2023.108477. eCollection 2024 Jan 19.

Authors

Joseph Lykins¹, Matthew J Moschitto², Ying Zhou³, Ekaterina V Filippova⁴, Hoang V Le², Tadakimi Tomita⁵, Barbara A Fox⁶, David J Bzik⁶, Chunlei Su⁷, Seesandra V Rajagopala⁸, Kristin Flores⁴, Furio Spano⁹, Stuart Woods¹⁰, Craig W Roberts¹⁰, Cong Hua³, Kamal El Bissati³, Kelsey M Wheeler³, Sarah Dovgin³, Stephen P Muench¹¹, Martin McPhillie¹², Colin W G Fishwick¹², Wayne F Anderson^{4

13}, Patricia J Lee¹⁴, Mark Hickman¹⁴, Louis M Weiss^{5

15}, Jitender P Dubey¹⁶, Hernan A Lorenzi⁸, Richard B Silverman^{2

13}, Rima L McLeod^{3

17}

Affiliations

¹ Pritzker School of Medicine, University of Chicago, Chicago, IL 60637, USA.
² Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208-3113, USA.
³ Department of Ophthalmology and Visual Sciences, The University of Chicago, Chicago, IL 60637, USA.
⁴ Center for Structural Genomics of Infectious Diseases and the Department of Biochemistry and Molecular Genetics, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
⁵ Division of Parasitology, Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
⁶ Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA.
⁷ Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
⁸ Department of Infectious Diseases, The J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850, USA.
⁹ Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy.
¹⁰ Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow Scotland, UK.
¹¹ School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, The University of Leeds, Leeds, West York LS2 9JT, UK.
¹² School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
¹³ Department of Pharmacology, Northwestern University, Chicago, IL 60611, USA.
¹⁴ Division of Experimental Therapeutics, Military Malaria Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
¹⁵ Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
¹⁶ Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA.
¹⁷ Department of Pediatrics (Infectious Diseases), Institute of Genomics, Genetics, and Systems Biology, Global Health Center, Toxoplasmosis Center, CHeSS, The College, University of Chicago, Chicago, IL 60637, USA.

Abstract

Toxoplasma gondii causes morbidity, mortality, and disseminates widely via cat sexual stages. Here, we find T. gondii ornithine aminotransferase (OAT) is conserved across phyla. We solve TgO/GABA-AT structures with bound inactivators at 1.55 Å and identify an inactivator selective for TgO/GABA-AT over human OAT and GABA-AT. However, abrogating TgO/GABA-AT genetically does not diminish replication, virulence, cyst-formation, or eliminate cat's oocyst shedding. Increased sporozoite/merozoite TgO/GABA-AT expression led to our study of a mutagenized clone with oocyst formation blocked, arresting after forming male and female gametes, with "Rosetta stone"-like mutations in genes expressed in merozoites. Mutations are similar to those in organisms from plants to mammals, causing defects in conception and zygote formation, affecting merozoite capacitation, pH/ionicity/sodium-GABA concentrations, drawing attention to cyclic AMP/PKA, and genes enhancing energy or substrate formation in TgO/GABA-AT-related-pathways. These candidates potentially influence merozoite's capacity to make gametes that fuse to become zygotes, thereby contaminating environments and causing disease.

Keywords: Cell biology; Parasitology.

Abstract

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