title: Thermodynamics of molecular recognition of mRNA 5' cap by yeast eukaryotic initiation factor 4E.
abstract: Molecular mechanisms underlying the recognition of the mRNA 5' terminal structure called "cap" by the eukaryotic initiation factor 4E (eIF4E) are crucial for cap-dependent translation. To gain a deeper insight into how the yeast eIF4E interacts with the cap structure, isothermal titration calorimetry and the van't Hoff analysis based on intrinsic protein fluorescence quenching upon titration with a series of chemical cap analogs were performed, providing a consistent thermodynamic description of the binding process in solution. Equilibrium association constants together with thermodynamic parameters revealed similarities and differences between yeast and mammalian eIF4Es. The yeast eIF4E complex formation was enthalpy-driven and entropy-opposed for each cap analog at 293 K. A nontrivial isothermal enthalpy–entropy compensation was found, described by a compensation temperature, T(c) = 411 ± 18 K. For a low affinity analog, 7-methylguanosine monophosphate, a heat capacity change was detected, ΔC(p)° = +5.2 ± 1.3 kJ·mol(-1)·K(-1). The charge-related interactions involving the 5′-5′ triphosphate bridge of the cap and basic amino acid side chains at the yeast eIF4E cap-binding site were significantly weaker (by ΔΔH°(vH) of about +10 kJ·mol(-1)) than those for the mammalian homologues, suggesting their optimization during the evolution.
authors.affiliation: Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089 Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kiraga-Motoszko
authors.forename: Anna
authors.initials: A
authors.lastname: Niedzwiecka
authors.forename: Anna
authors.initials: A
authors.lastname: Modrak-Wojcik
authors.forename: Janusz
authors.initials: J
authors.lastname: Stepinski
authors.forename: Edward
authors.initials: E
authors.lastname: Darzynkiewicz
authors.forename: Ryszard
authors.initials: R
authors.lastname: Stolarski
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D039561:Eukaryotic Initiation Factor-4E / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011485:Protein Binding; D012314:RNA Cap Analogs / Q000737:chemistry / Q000378:metabolism; D012315:RNA Caps / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D012314:RNA Cap Analogs; D012315:RNA Caps; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins