Characterization of human malaria parasite Plasmodium falciparum eIF4E homologue and mRNA 5' cap status.

The mRNA 5' cap is an essential structural feature for translation of eukaryotic mRNA. Translation is initiated by recognition of the cap by the translation initiation factor eIF4E. To further our understanding of mRNA translation in the human malaria parasite Plasmodium falciparum, we have investigated the parasite eIF4E and its interaction with capped mRNA. We have purified P. falciparum eIF4E as a recombinant protein and demonstrated that it has canonical mRNA cap binding activity. We used this protein to purify P. falciparum capped mRNAs from total parasite RNA. Microarray analysis comparing total and eIF4E-purified capped mRNAs shows that 34 features were more than twofold under-represented in the purified RNA sample, including 19 features representative of nuclear transcripts. The putatively uncapped nuclear transcripts may represent a class of mRNAs targeted for storage and cap removal.