Identification of a dithiol-dependent nucleoside triphosphate hydrolase in Sarcocystis neurona

Deqing Zhang, Rajshekhar Y. Gaji, Daniel K. Howe

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

A putative nucleoside triphosphate hydrolase (NTPase) gene was identified in a database of expressed sequence tags (ESTs) from the apicomplexan parasite Sarcocystis neurona. Analysis of culture-derived S. neurona merozoites demonstrated a dithiol-dependent NTPase activity, consistent with the presence of a homologue to the TgNTPases of Toxoplasma gondii. A complete cDNA was obtained for the S. neurona gene and the predicted amino acid sequence shared 38% identity with the two TgNTPase isoforms from T. gondii. Based on the obvious homology, the S. neurona protein was designated SnNTP1. The SnNTP1 cDNA encodes a polypeptide of 714 amino acids with a predicted 22-residue signal peptide and an estimated mature molecular mass of 70 kDa. Southern blot analysis of the SnNTP1 locus revealed that the gene exists as a single copy in the S. neurona genome, unlike the multiple gene copies that have been observed in T. gondii and Neospora caninum. Analyses of the SnNTP1 protein demonstrated that it is soluble and secreted into the culture medium by extracellular merozoites. Surprisingly, indirect immunofluorescence analysis of intracellular S. neurona revealed apical localisation of SnNTP1 and temporal expression characteristics that are comparable with the microneme protein SnMIC10. The absence of SnNTP1 during much of endopolygeny implies that this protein does not serve a function during intracellular growth and development of S. neurona schizonts. Instead, SnNTP1 may play a role in events that occur during or proximal to merozoite egress from and/or invasion into cells.

Original languageEnglish
Pages (from-to)1197-1204
Number of pages8
JournalInternational Journal for Parasitology
Volume36
Issue number10-11
DOIs
StatePublished - Sep 2006

Bibliographical note

Funding Information:
This work was supported by grants from the Amerman Family Foundation and Fort Dodge Animal Health and gifts from various donors. It was published as Kentucky Agricultural Experiment Station Article No. 06-14-031.

Keywords

  • Apicomplexa
  • Cell invasion
  • Equine protozoal myeloencephalitis
  • Expressed sequence tag
  • Microneme
  • Nucleoside triphosphate hydrolase
  • Virulence factor

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases

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