title: Dynamic recognition of the mRNA cap by Saccharomyces cerevisiae eIF4E.
abstract: Recognition of the mRNA 5' m⁷G(5')ppp(5')N cap is key to translation initiation for most eukaryotic mRNAs. The cap is bound by the eIF4F complex, consisting of a cap-binding protein (eIF4E), a "scaffold" protein (eIF4G), and an RNA helicase (eIF4A). As a central early step in initiation, regulation of eIF4F is crucial for cellular viability. Although the structure and function of eIF4E have been defined, a dynamic mechanistic picture of its activity at the molecular level in the eIF4F·mRNA complex is still unavailable. Here, using single-molecule fluorescence, we measured the effects of Saccharomyces cerevisiae eIF4F factors, mRNA secondary structure, and the poly(A)-binding protein Pab1p on eIF4E-mRNA binding dynamics. Our data provide an integrated picture of how eIF4G and mRNA structure modulate eIF4E-mRNA interaction, and uncover an eIF4G- and poly(A)-independent activity of poly(A)-binding protein that prolongs the eIF4E·mRNA complex lifetime.
authors.affiliation: Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Seán E
authors.initials: SE
authors.lastname: O'Leary
authors.forename: Alexey
authors.initials: A
authors.lastname: Petrov
authors.forename: Jin
authors.initials: J
authors.lastname: Chen
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Puglisi
mesh_terms: D002232:Carbocyanines; D039561:Eukaryotic Initiation Factor-4E / Q000737:chemistry*; D039603:Eukaryotic Initiation Factor-4G / Q000737:chemistry / Q000378:metabolism; D005095:Exoribonucleases / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D009690:Nucleic Acid Conformation; D010442:Peptide Chain Initiation, Translational; D011061:Poly A / Q000737:chemistry; D039102:Poly(A)-Binding Proteins / Q000737:chemistry; D012315:RNA Caps / Q000737:chemistry*; D012331:RNA, Fungal / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry
chemical_list: D002232:Carbocyanines; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D005456:Fluorescent Dyes; D039102:Poly(A)-Binding Proteins; D012315:RNA Caps; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; C085321:cyanine dye 5; C450100:pab1 protein, S cerevisiae; D011061:Poly A; D005095:Exoribonucleases; C101747:PAN3 protein, S cerevisiae