Folding transitions during assembly of the eukaryotic mRNA cap-binding complex.
The cap-binding protein eIF4E is the first in a chain of translation initiation factors that recruit 40S ribosomal subunits to the 5' end of eukaryotic mRNA. During cap-dependent translation, this protein binds to the 5'-terminal m(7)Gppp cap of the mRNA, as well as to the adaptor protein eIF4G. The latter then interacts with small ribosomal subunit-bound proteins, thereby promoting the mRNA recruitment process. Here, we show apo-eIF4E to be a protein that contains extensive unstructured regions, which are induced to fold upon recognition of the cap structure. Binding of eIF4G to apo-eIF4E likewise induces folding of the protein into a state that is similar to, but not identical with, that of cap-bound eIF4E. At the same time, binding of each of the binding partners of eIF4E modulates the kinetics with which it interacts with the other partner. We present structural, kinetic and mutagenesis data that allow us to deduce some of the detailed folding transitions that take place during the eIF4E interactions.
von der Haar
Tobias
T
Manchester Interdisciplinary Biocentre, c/o Jackson's Mill, University of Manchester, P.O. Box 88, Manchester M60 1QD, UK. t.von-der-haar@kent.ac.uk
Oku
Yuko
Y
Ptushkina
Marina
M
Moerke
Nathan
N
Wagner
Gerhard
G
Gross
John D
JD
McCarthy
John E G
JE
D000595:Amino Acid Sequence; D039561:Eukaryotic Initiation Factor-4E / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D039603:Eukaryotic Initiation Factor-4G / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017510:Protein Folding; D012315:RNA Caps / Q000737:chemistry*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance
D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D012315:RNA Caps; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins