Toxoplasma gondii: Molecular Cloning and Characterization of a Novel 18-kDa Secretory Antigen, TgMIC10

• Published in: Experimental parasitology Vol. 97; no. 2; pp. 77 - 88
• Main Authors: Hoff, Eleanor F., Cook, Susan H., Sherman, Gale D., Harper, Jill M., Ferguson, David J.P., Dubremetz, Jean-Fraņcois, Carruthers, Vern B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-02-2001
• Subjects: Amino Acid Sequence; Animals; Antigens, Protozoan - chemistry; Antigens, Protozoan - genetics; Apicomplexa; BAPTA-AM, 1,2-bis(o-aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid tetra-(acetoxymethyl) ester; Base Sequence; BFA, brefeldin A; CSPD, disodium 3-(4-methoxyspiro{1,2-dioxetane-3,2′-(5′-chloro)tricyclo-[3.3.1.13,7]decan}-4-yl) phenyl phosphate; DMEM, Dulbecco's Modified Eagle's Medium; DNA, deoxyribonucleic acid; ESA, excreted/secreted antigen; EST, expressed sequence tag; EtOH, ethanol; invasion; Mice; micronemes; Molecular Sequence Data; NcMIC10 antigen; Organelles - chemistry; Protozoan Proteins - chemistry; Protozoan Proteins - genetics; Rabbits; Rats; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; Sequence Alignment; TgMIC10 antigen; Toxoplasma - genetics; Toxoplasma - immunology; Toxoplasma gondii; toxoplasmosis; Apicomplexa; DMEM, Dulbecco's Modified Eagle's Medium; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; BAPTA-AM, 1,2-bis(o-aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid tetra-(acetoxymethyl) ester; EtOH, ethanol; EST, expressed sequence tag; BFA, brefeldin A; Toxoplasma gondii; invasion; CSPD, disodium 3-(4-methoxyspiro{1,2-dioxetane-3,2′-(5′-chloro)tricyclo-[3.3.1.13,7]decan}-4-yl) phenyl phosphate; ESA, excreted/secreted antigen; micronemes; DNA, deoxyribonucleic acid
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1006/expr.2000.4585

Hoff, E. F., Cook, S. H., Sherman, G. D., Harper, J. M., Ferguson, D. J. P., Dubremetz, J. F., and Carruthers, V. B. 2001. Toxoplasma gondii: Molecular cloning and characterization of a novel 18-kDa secretory antigen, TgMIC10. Experimental Parasitology,97, 77–88. During host cell invasion, Toxoplasma gondii secretes proteins from specialized organelles (micronemes and rhoptries) located at the apical end of the parasite. The contents of the micronemes appear to be crucial to T. gondii invasion, as inhibition of microneme secretion prevents parasite entry into host cells. Here we describe a new T. gondii microneme protein, TgMIC10. Molecular characterization of a full-length TgMIC10 cDNA revealed that TgMIC10 lacks homology to any previously characterized proteins, although a homologue, NcMIC10, was identified in a closely related parasite, Neospora caninum. TgMIC10 has an unusually long secretory leader sequence of 58 amino acids; the mature TgMIC10 is 18 kDa, possesses nine diglutamic acid repeats and an imperfect repeat sequence (RK(R/Y)HEEL), and is entirely devoid of cysteines. Antibodies raised against recombinant TgMIC10 recognized the native TgMIC10 and localized the protein to the micronemes in indirect immunofluorescence and immunoEM experiments. Comparison of immunofluorescence images indicates that TgMIC10 expression is higher in T. gondii tachyzoites, which are responsible for active infection, than in bradyzoites, which are responsible for latent infection.