title: The aromatic amino acid hydroxylase genes AAH1 and AAH2 in Toxoplasma gondii contribute to transmission in the cat.
abstract: The Toxoplasma gondii genome contains two aromatic amino acid hydroxylase genes, AAH1 and AAH2 encode proteins that produce L-DOPA, which can serve as a precursor of catecholamine neurotransmitters. It has been suggested that this pathway elevates host dopamine levels thus making infected rodents less fearful of their definitive Felidae hosts. However, L-DOPA is also a structural precursor of melanins, secondary quinones, and dityrosine protein crosslinks, which are produced by many species. For example, dityrosine crosslinks are abundant in the oocyst walls of Eimeria and T. gondii, although their structural role has not been demonstrated, Here, we investigated the biology of AAH knockout parasites in the sexual reproductive cycle within cats. We found that ablation of the AAH genes resulted in reduced infection in the cat, lower oocyst yields, and decreased rates of sporulation. Our findings suggest that the AAH genes play a predominant role during infection in the gut of the definitive feline host.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Zi T
authors.identifier: 0000-0001-6302-2125
authors.initials: ZT
authors.lastname: Wang
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland, United States of America.
authors.forename: Shiv K
authors.initials: SK
authors.lastname: Verma
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland, United States of America.
authors.forename: Jitender P
authors.initials: JP
authors.lastname: Dubey
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: L David
authors.identifier: 0000-0001-7110-0285
authors.initials: LD
authors.lastname: Sibley
mesh_terms: D024322:Amino Acids, Aromatic; D000818:Animals; D002415:Cats; D017125:Genes, Protozoan / Q000502:physiology*; D051379:Mice; D008856:Microscopy, Fluorescence; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D033661:Oocysts / Q000469:parasitology; D030781:Organisms, Genetically Modified; D014122:Toxoplasma / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D014124:Toxoplasmosis, Animal / Q000635:transmission*
chemical_list: D024322:Amino Acids, Aromatic; D006899:Mixed Function Oxygenases