title: Eimeria tenella microneme protein EtMIC4: capture of the full-length transcribed sequence and comparison with other microneme proteins.
abstract: EtMIC4 is a microneme protein of Eimeria tenella, an intracellular apicomplexan protozoan that can cause severe enteritis in chickens. The EtMIC4 gene has been partially characterised, and in this study, we used a combined strategy of rapid amplification of cDNA ends (5'RACE) and reverse transcription-polymerase chain reaction to identify the authentic 5' end of the transcribed sequence (accession number AJ306453.2). Comparison of the predicted EtMIC4 transcription start site with predicted start sites for EtMIC1, 2 and 3 genes identified comparable initiator regions that each conform to the consensus sequence for a transcriptional initiator element. The EtMIC4 gene is organised over 11 exons and analysis of the full-length predicted protein identified a new N-terminal region that comprises a hydrophobic signal peptide followed by four thrombospondin-type 1 modules that are similar to those previously described further downstream in the protein. Best-fit analysis shows that EtMIC4 shares high homology with the Eimeria maxima protein EmTFP250 and with TgMIC12, a predicted Toxoplasma gondii microneme protein. EtMIC4 and EmTFP250 share 70% amino acid identity and all predicted structural domains are conserved between the two. EtMIC4 and TgMIC12 share 48% identity and they have very similar domain organisation and conservation of intron/exon boundaries.
authors.affiliation: Institute for Animal Health, Compton, Newbury, Berkshire, RG20 7NN, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: Periz
authors.forename: Rachael
authors.initials: R
authors.lastname: Ryan
authors.forename: Damer P
authors.initials: DP
authors.lastname: Blake
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Tomley
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D016786:Eimeria tenella / Q000235:genetics*; D005091:Exons; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014122:Toxoplasma / Q000235:genetics; D024363:Transcription Initiation Site
chemical_list: D015815:Cell Adhesion Molecules; D016054:DNA, Protozoan; D021382:Protein Sorting Signals; D015800:Protozoan Proteins