Four abundant novel transcript genes from Toxocara canis with unrelated coding sequences share untranslated region tracts implicated in the control of gene expression

Callister, D. M., Winter, A. D., Page, A. P. and Maizels, R. M. (2008) Four abundant novel transcript genes from Toxocara canis with unrelated coding sequences share untranslated region tracts implicated in the control of gene expression. Molecular and Biochemical Parasitology, 162(1), pp. 60-70. (doi: 10.1016/j.molbiopara.2008.07.004)

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Publisher's URL: http://dx.doi.org/10.1016/j.molbiopara.2008.07.004

Abstract

The Toxocara canis "abundant novel transcripts" (ant) are four highly expressed products, constituting >18% of ESTs from the infective stage of this widely prevalent nematode parasite. Using 5' RACE, we determined full-length sequences for each ant gene, between 1.8 and 2.8kb. The four genes (termed ant-3, -5, -30 and -34), share no coding sequence similarity, although their 3'UTRs (untranslated regions) are homologous. Predicted ANT-5 and ANT-30 proteins show distant similarity to RNA regulatory proteins, RNA-dependent RNA polymerase and DEAH-box helicase, respectively. Surprisingly, ant-3 appears to be bi-cistronic, encoding two ORFs (ANT-3.1 and -3.2), each with a predicted N-terminal signal sequence. Antibodies raised to recombinant proteins did not react with native parasite products, indicating that protein expression did not accord with transcript abundance. However, antibody reactivity to two gene products (ANT-3.1 and ANT-34) was present in patient sera, suggesting that these proteins are synthesized later in infection. To test whether 3'UTRs may regulate expression, the ant-34 3'UTR sequence was inserted adjacent to enhanced green fluorescent protein (EGFP) for transformation of Caenorhabditis elegans. The ant-34 3'UTR greatly reduced EGFP expression, inhibiting both transcription and translation. We identified a tract in this UTR with significant sequence complementarity to the C. elegans micro-RNA lin-4. While infective stage parasites stockpile high levels of the ant transcripts, we suggest that translation is repressed, possibly by a mechanism involving 3' UTR motifs shared by the four genes.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Page, Professor Tony and Winter, Dr Alan
Authors: Callister, D. M., Winter, A. D., Page, A. P., and Maizels, R. M.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Molecular and Biochemical Parasitology
Publisher:Elsevier BV
ISSN:0166-6851
ISSN (Online):1872-9428
Published Online:25 July 2008
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
229991The Molecular Enzymology of Collagen Assembly and Post-Translational Modification: a Nematode Model SystemAntony PageMedical Research Council (MRC)G117/290Infection Immunity and Inflammation Life Sciences
229993The Molecular Enzymology of Collagen Assembly and Post-Translational Modification: a Nematode Model SystemAntony PageMedical Research Council (MRC)G117/476III - PARASITOLOGY