title: A conserved U-rich RNA region implicated in regulation of translation in Plasmodium female gametocytes.
abstract: Translational repression (TR) plays an important role in post-transcriptional regulation of gene expression and embryonic development in metazoans. TR also regulates the expression of a subset of the cytoplasmic mRNA population during development of fertilized female gametes of the unicellular malaria parasite, Plasmodium spp. which results in the formation of a polar and motile form, the ookinete. We report the conserved and sex-specific regulatory role of either the 3'- or 5'-UTR of a subset of translationally repressed mRNA species as shown by almost complete inhibition of expression of a GFP reporter protein in the female gametocyte. A U-rich, TR-associated element, identified previously in the 3'-UTR of TR-associated transcripts, played an essential role in mediating TR and a similar region could be found in the 5'-UTR shown in this study to be active in TR. The silencing effect of this 5'-UTR was shown to be independent of its position relative to its ORF, as transposition to a location 3' of the ORF did not affect TR. These results demonstrate for the first time in a unicellular organism that the 5' or the 3'-UTR of TR-associated transcripts play an important and conserved role in mediating TR in female gametocytes.
authors.affiliation: Department of Parasitology, Centre of Infectious Diseases, Leiden University Medical Centre (LUMC), Leiden, The Netherlands.
authors.forename: Joanna A M
authors.initials: JA
authors.lastname: Braks
authors.forename: Gunnar R
authors.initials: GR
authors.lastname: Mair
authors.forename: Blandine
authors.initials: B
authors.lastname: Franke-Fayard
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Janse
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Waters
mesh_terms: D020413:3' Untranslated Regions / Q000737:chemistry*; D020121:5' Untranslated Regions / Q000737:chemistry*; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D010063:Ovum / Q000254:growth & development / Q000378:metabolism*; D010962:Plasmodium berghei / Q000235:genetics* / Q000254:growth & development; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D016053:RNA, Protozoan / Q000737:chemistry; D038621:Regulatory Sequences, Ribonucleic Acid; D014529:Uridine / Q000032:analysis
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D012333:RNA, Messenger; D016053:RNA, Protozoan; D038621:Regulatory Sequences, Ribonucleic Acid; D049452:Green Fluorescent Proteins; D014529:Uridine