Structural and thermodynamic behavior of eukaryotic initiation factor 4E in supramolecular formation with 4E-binding protein 1 and mRNA cap analogue, studied by spectroscopic methods.

摘要: The structural and thermodynamic behavior of the complex formation eIF4E with either or both mRNA cap analogue (m7GTP, m7GpppA, m7GpppG) 4EBP1 has been investigated by spectroscopic measurements. Although circular dichroism (CD) spectrum was little affected association any analogue, constant m7GpppA/G, estimated from fluorescence quenching, about 10 times larger than that m7GTP. van't Hoff analyses showed m7GpppA/G binding is enthalpy-driven a large negative deltaH(o), this in contrast entropy-driven m7GTP, where positive deltaS(o) enough to overcome an increase deltaH(o). This different obviously originates interaction second nucleotide m7GpppA eIF4E, suggesting importance sequence linked m7Gppp terminal moiety, addition specific m7G base, for recognition structure eIF4E. On other hand, CD spectra indicated 4EBP1, endogenous eIF4E-regulatory protein without having defined secondary structure, shifted m7GTP- m7GpppA/G-bound irregular although such change not observed alone. two orders magnitude These results suggest close interrelation supramolecular 4EBP-eIF4E-mRNA structure.