1 H, 13 C, and 15 N backbone chemical shift assignments of m 7 GTP cap-bound Leishmania initiation factor 4E-1
- PDF / 1,047,916 Bytes
- 5 Pages / 595.276 x 790.866 pts Page_size
- 48 Downloads / 183 Views
ARTICLE
1
H, 13C, and 15N backbone chemical shift assignments of m7GTP capbound Leishmania initiation factor 4E-1
Anissa Belfetmi1 · Mélissa Léger‑Abraham1 Received: 29 April 2020 / Accepted: 2 June 2020 © The Author(s) 2020
Abstract Most of the translational control of gene expression in higher eukaryotes occurs during the initiation step of protein synthesis. While this process is well characterized in mammalian cells, it is less defined in parasites, including the ones that cause human Leishmaniasis. The Leishmania cap-binding isoform 1 (LeishIF4E-1) is the only isoform that binds the specific trypanosomatids-specific hypermethylated 5′ cap, called cap-4, in the human stage of the parasite life cycle. We report here the extensive NMR resonance assignment of LeishIF4E-1 bound to a cap analog, m 7GTP. The chemical shift data constitute a prerequisite to understanding specific translation initiation mechanisms used in Leishmania parasites and to developing antiparasitic drugs targeting their translation initiation factors. Keywords Leishmania · Translation initiation · LeishIF4E-1 · NMR
Biological context The translation initiation heterotrimeric complex, eIF4F, recruits the 5′ end of mRNAs to the small ribosomal subunit (Shirokikh and Preiss 2018). In human cells, this complex comprises a cap-binding protein, eIF4E, which specifically binds a methylated cap structure (m7GTP) at the 5′ end of most cellular mRNAs. A scaffold protein, eIF4G, binds eIF4E, the DEAD-box RNA helicase eIF4A, the poly-A binding protein PABP, and the multisubunit eIF3, which binds to the small ribosomal subunit. eIF4G interacts with eIF4E through a consensus motif, Y(X)4LΦ (where X is any amino acid and Φ is a hydrophobic residue). Despite our increasing knowledge of translation mechanisms in human cells, how the equivalent process is carried out in trypanosomatids, including Leishmania major, is not as well understood. The specific factors involved in translation initiation vary depending on the developmental stage of Leishmania parasites. These parasites encode six highly diverged capbinding protein isoforms (LeishIF4E-1 through −6) that significantly differ among themselves and from their orthologs
in mammalian cells (Yoffe et al. 2004, 2006, 2009; Zinoviev et al. 2011). Trypanosomatids also contain a specific hypermethylated cap structure at the 5′ end of their mRNAs, called cap-4 (Reolon et al. 2019; Leiter et al. 2020). In the human developmental stage of the parasite’s life cycle, LeishIF4E-1 is the only isoform that is highly expressed and maintains cap-binding activity, suggesting that it is the functional capbinding protein in the human infective stage (Zinoviev et al. 2011). LeishIF4E-1 does not, however, interact with any of the predicted LeishIF4G scaffold proteins, suggesting that LeishIF4E-1 is recruited to the LeishIF4F translation initiation complex through novel interactions, or that translation initiation in amastigotes proceeds through a cap-independent mechanism. A crystal structure of LeishIF4E-1 bound to
Data Loading...
