title: Poly(A)-binding protein I of Leishmania: functional analysis and localisation in trypanosomatid parasites.
abstract: Regulation of gene expression in trypanosomatid parasites is predominantly post-transcriptional. Primary transcripts are trans-spliced and polyadenylated to generate mature mRNAs and transcript stability is a major factor controlling stage-specific gene expression. Degenerate PCR has been used to clone the gene encoding the Leishmania homologue of poly(A)-binding protein (Lm PAB1), as an approach to the identification of trans-acting factors involved in this atypical mode of eukaryotic gene expression. lmpab1 is a single copy gene encoding a 63 kDa protein which shares major structural features but only 35-40% amino acid identity with other PAB1 sequences, including those of other trypanosomatids. Lm PAB1 is expressed at constant levels during parasite differentiation and is phosphorylated in vivo. It is localised predominantly in the cytoplasm but inhibition of transcription with actinomycin D also reveals diffuse localisation in the nucleus. Lm PAB1 binds poly(A) with high specificity and affinity but fails to complement a null mutation in Saccharomyces cerevisiae. These properties are indicative of functional divergence in vivo.
authors.affiliation: Wellcome Laboratories for Molecular Parasitology, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: Bates
authors.forename: E
authors.initials: E
authors.lastname: Knuepfer
authors.forename: D F
authors.initials: DF
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007891:Leishmania / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D039102:Poly(A)-Binding Proteins; D015800:Protozoan Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017421:Sequence Analysis; D015398:Signal Transduction
chemical_list: D039102:Poly(A)-Binding Proteins; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins