title: Diverse cap-binding properties of Drosophila eIF4E isoforms.
abstract: The majority of eukaryotic mRNAs are translated in a cap-dependent manner, which requires recognition of the mRNA 5' cap by eIF4E protein. Multiple eIF4E family members have been identified in most eukaryotic organisms. Drosophila melanogaster (Dm) has eight eIF4E related proteins; seven of them belong to Class I and one to Class II. Their biological roles with the exception of Dm eIF4E-1, Dm eIF4E-3 and Dm 4EHP, remain unknown. Here, we compare the molecular basis of Dm eIF4E's interactions with cap and eIF4G peptide by using homology modelling and fluorescence binding assays with various cap analogues. We found that despite the presence of conserved key residues responsible for cap recognition, the differences in binding different cap analogues among Class I Dm eIF4E isoforms are up to 14-fold. The highest affinity for cap analogues was observed for Dm eIF4E-3. We suggest that Dm eIF4E-3 and Dm eIF4E-5 bind the second nucleoside of the cap in an unusual manner via stacking interactions with a histidine or a phenylalanine residue, respectively. Moreover, the analysis of ternary complexes of eIF4G peptide-eIF4E-cap analogue showed cooperativity between eIF4G and cap binding only for Dm eIF4E-4, which exhibits the lowest affinity for cap analogues among all Dm eIF4Es.
authors.affiliation: Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland. Electronic address: jzuberek@biogeo.uw.edu.pl.
authors.forename: Joanna
authors.initials: J
authors.lastname: Zuberek
authors.affiliation: Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw 02-089, Poland. Electronic address: kuchtak@cent.uw.edu.pl.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kuchta
authors.affiliation: Division of Basic Research, National Institute of Cancer (INCan), Tlalpan, Mexico City 14080, Mexico. Electronic address: greco.hernandez@gmail.com.
authors.forename: Greco
authors.initials: G
authors.lastname: Hernández
authors.affiliation: Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada. Electronic address: nahum.sonenberg@mcgill.ca.
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.affiliation: Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland. Electronic address: kginal@cent.uw.edu.pl.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Ginalski
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D004331:Drosophila melanogaster / Q000378:metabolism*; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D008958:Models, Molecular; D010455:Peptides / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D020033:Protein Isoforms / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012314:RNA Cap Analogs / Q000378:metabolism; D012315:RNA Caps / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D010455:Peptides; D020033:Protein Isoforms; D012314:RNA Cap Analogs; D012315:RNA Caps; D010649:Phenylalanine; D006639:Histidine
keywords: Cap analogues; Fluorescence spectroscopy; Protein-ligand interactions; Translation initiation; eIF4E family