Poly(A)-binding proteins in trypanosomatids and Plasmodium

Poly(A)-binding proteins (PABPs) are scaffold proteins that bind to the poly(A) tail of mRNAs and ensure translation fidelity by forming a closed-loop circular mRNA via association with the cap-binding complex. They can be either cytoplasmic or nuclear and play important roles in regulating polyadenylation, deadenylation, translation initiation and termination, mRNA stability, synthesis of the poly(A) tail, regulation of poly(A) length and stimulation of mRNA maturation as well as nuclear export of certain mRNAs. In higher eukaryotes, PABPs are well characterized. However, in pathogenic parasites such as trypanosomatids, belonging to the genera Leishmania and Trypanosoma, as well as Plasmodium, they are not well characterized. Using bioinformatics and computational tools, we have previously studied parasite translation initiation factors such as eIF4E, eIF4G, eIF4A, eIF4B, and Mnk1 kinase and have shown that they vary considerably and differ significantly from human translation initiation factors. In this report, the orthologues of the translation factor PABP in trypanosomatids and Plasmodium are studied. Both conservation and significant differences were observed in PABPs from these pathogenic parasites compared to human PABPs, which should prompt further structure-function studies of these proteins.