title: Two COWP-like cysteine rich proteins from Eimeria nieschulzi (coccidia, apicomplexa) are expressed during sporulation and involved in the sporocyst wall formation.
abstract: BACKGROUND
  The family of cysteine rich proteins of the oocyst wall (COWPs) originally described in Cryptosporidium can also be found in Toxoplasma gondii (TgOWPs) localised to the oocyst wall as well. Genome sequence analysis of Eimeria suggests that these proteins may also exist in this genus and led us to the assumption that these proteins may also play a role in oocyst wall formation.
  
  
  METHODS
  In this study, COWP-like encoding sequences had been identified in Eimeria nieschulzi. The predicted gene sequences were subsequently utilized in reporter gene assays to observe time of expression and localisation of the reporter protein in vivo.
  
  
  RESULTS
  Both investigated proteins, EnOWP2 and EnOWP6, were expressed during sporulation. The EnOWP2-promoter driven mCherry was found in the cytoplasm and the EnOWP2, respectively EnOWP6, fused to mCherry was initially observed in the extracytoplasmatic space between sporoblast and oocyst wall. This, so far unnamed compartment was designated as circumplasm. Later, the mCherry reporter co-localised with the sporocyst wall of the sporulated oocysts. This observation had been confirmed by confocal microscopy, excystation experiments and IFA. Transcript analysis revealed the intron-exon structure of these genes and confirmed the expression of EnOWP2 and EnOWP6 during sporogony.
  
  
  CONCLUSIONS
  Our results allow us to assume a role, of both investigated EnOWP proteins, in the sporocyst wall formation of E. nieschulzi. Data mining and sequence comparisons to T. gondii and other Eimeria species allow us to hypothesise a conserved process within the coccidia. A role in oocyst wall formation had not been observed in E. nieschulzi.
authors.affiliation: Institute for Zoology, Technische Universität Dresden, 01062, Dresden, Germany. ernst.jonscher@googlemail.com.
authors.forename: Ernst
authors.initials: E
authors.lastname: Jonscher
authors.affiliation: Institute for Zoology, Technische Universität Dresden, 01062, Dresden, Germany. Alexander.Erdbeer@gmx.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Erdbeer
authors.affiliation: Institute for Zoology, Technische Universität Dresden, 01062, Dresden, Germany. marieguenther93@gmx.de.
authors.forename: Marie
authors.initials: M
authors.lastname: Günther
authors.affiliation: Institute for Zoology, Technische Universität Dresden, 01062, Dresden, Germany. kurth.michael@googlemail.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Kurth
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism; D003048:Coccidiosis / Q000469:parasitology*; D003458:Cryptosporidium / Q000235:genetics / Q000378:metabolism; D003545:Cysteine; D003593:Cytoplasm / Q000378:metabolism; D004539:Eimeria / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D017930:Genes, Reporter; D018503:Genome, Protozoan / Q000235:genetics*; D008969:Molecular Sequence Data; D033661:Oocysts; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D015800:Protozoan Proteins; C106305:oocyst wall protein, Cryptosporidium; D003545:Cysteine