Biomaterial Database

Basis for substrate specificity of the Toxoplasma gondii nucleoside triphosphate hydrolase. 1998

V Nakaar, and C J Beckers, and V Polotsky, and K A Joiner

Department of Internal Medicine, Yale University School of Medicine, New Haven CT 06520-8022, USA.

The Toxoplasma gondii nucleoside triphosphate hydrolase is the most active E-type ATPase yet identified, and was the first member of this new gene family to be cloned (Bermudes D, Peck KR, Afifi-Afifi M, Beckers CJM, Joiner KA. J Biol Chem 1994;269:29252-29260. Previous work also identified two isoforms of the enzyme in the virulent RH strain, and demonstrated that internal fragments of the genes encoding these isoforms were found differentially in virulent versus avirulent organisms (Asai T, Miura S, Sibley D, Okabayashi H, Tsutomu T, J Biol Chem 1995;270:11391-11397). We now show that the NTPase 1 isoform is expressed in avirulent strains, whereas virulent strains express both the NTPase 1 and NTPase 3 isoforms. The avirulent PLK strain lacks the gene for NTPase 3, explaining the absence of expression. Despite the fact that NTPase 1 and NTPase 3 are 97% identical at the amino acid level, recombinant NTPase 1 is a true apyrase, whereas recombinant NTPase 3 cleaves predominantly nucleotide triphosphates. Furthermore, native and recombinant NTPase 3 but neither native nor recombinant NTPase 1 bind to ATP-agarose, further distinguishing the two isoforms. Using chimeras between the NTP1 and NTP3 genes, we show that a block of twelve residues at the C-terminus dictates substrate specificity. These residues lie outside the regions conserved among other E-ATPases, and therefore provide new insight into substrate recognition by this class of enzymes.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D002522	Chlorocebus aethiops	A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.	African Green Monkey,Cercopithecus aethiops,Cercopithecus griseoviridis,Cercopithecus griseus,Cercopithecus pygerythrus,Cercopithecus sabeus,Cercopithecus tantalus,Chlorocebus cynosuros,Chlorocebus cynosurus,Chlorocebus pygerythrus,Green Monkey,Grivet Monkey,Lasiopyga weidholzi,Malbrouck,Malbrouck Monkey,Monkey, African Green,Monkey, Green,Monkey, Grivet,Monkey, Vervet,Savanah Monkey,Vervet Monkey,Savannah Monkey,African Green Monkey,Chlorocebus cynosuro,Green Monkey, African,Green Monkeys,Grivet Monkeys,Malbrouck Monkeys,Malbroucks,Monkey, Malbrouck,Monkey, Savanah,Monkey, Savannah,Savannah Monkeys,Vervet Monkeys
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities
D014122	Toxoplasma	A genus of protozoa parasitic to birds and mammals. T. gondii is one of the most common infectious pathogenic animal parasites of man.	Toxoplasma gondii,Toxoplasma gondius,Toxoplasmas,gondius, Toxoplasma
D014709	Vero Cells	A CELL LINE derived from the kidney of the African green (vervet) monkey, (CHLOROCEBUS AETHIOPS) used primarily in virus replication studies and plaque assays.	Cell, Vero,Cells, Vero,Vero Cell