title: The PfAlba1 RNA-binding protein is an important regulator of translational timing in Plasmodium falciparum blood stages.
abstract: BACKGROUND
  Transcriptome-wide ribosome occupancy studies have suggested that during the intra-erythrocytic lifecycle of Plasmodium falciparum, select mRNAs are post-transcriptionally regulated. A subset of these encodes parasite virulence factors required for invading host erythrocytes, and are currently being developed as vaccine candidates. However, the molecular mechanisms that govern post-transcriptional regulation are currently unknown.
  
  
  RESULTS
  We explore the previously identified DNA/RNA-binding protein PfAlba1, which localizes to multiple foci in the cytoplasm of P. falciparum trophozoites. We establish that PfAlba1 is essential for asexual proliferation, and subsequently investigate parasites overexpressing epitope-tagged PfAlba1 to identify its RNA targets and effects on mRNA homeostasis and translational regulation. Using deep sequencing of affinity-purified PfAlba1-associated RNAs, we identify 1193 transcripts that directly bind to PfAlba1 in trophozoites. For 105 such transcripts, 43 % of which are uncharacterized and 13 % of which encode erythrocyte invasion components, the steady state levels significantly change at this stage, evidencing a role for PfAlba1 in maintaining mRNA homeostasis. Additionally, we discover that binding of PfAlba1 to four erythrocyte invasion mRNAs, Rap1, RhopH3, CDPK1, and AMA1, is linked to translation repression in trophozoites whereas release of these mRNAs from a PfAlba1 complex in mature stages correlates with protein synthesis.
  
  
  CONCLUSIONS
  We show that PfAlba1 binds to a sub-population of asexual stage mRNAs and fine-tunes the timing of translation. This mode of post-transcriptional regulation may be especially important for P. falciparum erythrocyte invasion components that have to be assembled into apical secretory organelles in a highly time-dependent manner towards the end of the parasite's asexual lifecycle.
authors.affiliation: Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, 75015, France. shruthi-sridhar.vembar@pasteur.fr.|CNRS, ERL 9195, Paris, 75015, France. shruthi-sridhar.vembar@pasteur.fr.|INSERM, UMR 1201, Paris, 75015, France. shruthi-sridhar.vembar@pasteur.fr.
authors.forename: Shruthi Sridhar
authors.initials: SS
authors.lastname: Vembar
authors.affiliation: Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, 75015, France.|CNRS, ERL 9195, Paris, 75015, France.|INSERM, UMR 1201, Paris, 75015, France.
authors.forename: Cameron Ross
authors.initials: CR
authors.lastname: Macpherson
authors.affiliation: Plate-forme 2, Transcriptome et Epigenome, Institut Pasteur, Paris, 75015, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Sismeiro
authors.affiliation: Plate-forme 2, Transcriptome et Epigenome, Institut Pasteur, Paris, 75015, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Coppée
authors.affiliation: Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, 75015, France. artur.scherf@pasteur.fr.|CNRS, ERL 9195, Paris, 75015, France. artur.scherf@pasteur.fr.|INSERM, UMR 1201, Paris, 75015, France. artur.scherf@pasteur.fr.
authors.forename: Artur
authors.initials: A
authors.lastname: Scherf
mesh_terms: D000818:Animals; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology; D005786:Gene Expression Regulation; D059014:High-Throughput Nucleotide Sequencing; D006790:Host-Parasite Interactions / Q000235:genetics; D006801:Humans; D016778:Malaria, Falciparum / Q000235:genetics* / Q000469:parasitology; D010963:Plasmodium falciparum / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics*; D053058:Trophozoites / Q000378:metabolism / Q000469:parasitology
chemical_list: D015800:Protozoan Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins