The Leishmania PABP1–eIF4E4 interface: a novel 5’–3’ interaction architecture for trans-spliced mRNAs
Trans-splicing of trypanosomatid polycistronic transcripts produces polyadenylated monocistronic mRNAs modiﬁed to form the 5’ cap4 structure. Leishmania has a unique type of N-terminally-extended cap-binding protein (eIF4E4) that binds via a PAM2 motif to PABP1. This relies on the interactions of a combination of polar and charged amino acid side-chains together with multiple hydrophobic interactions, and underpins a novel architecture in the Leishmania cap4-binding translation factor complex. In Leishmania , the chain of interactions 5’cap4-eIF4E4–PABP1-poly(A) bridges the mRNA 5’ and 3ends.