TY - JOUR
T1 - Local control of a disorder-order transition in 4E-BP1 underpins regulation of translation via eIF4E
AU - Tait, Shirley
AU - Dutta, Kaushik
AU - Cowburn, David
AU - Warwicker, Jim
AU - Doig, Andrew J.
AU - McCarthy, John E.G.
PY - 2010/10/12
Y1 - 2010/10/12
N2 - The molecular mechanism underpinning regulation of eukaryotic translation initiation factor eIF4E by 4E-BP1 has remained unclear. We use isothermal calorimetry, circular dichroism, NMR, and computational modeling to analyze how the structure of the eIF4E-binding domain of 4E-BP1 determines its affinity for the dorsal face of eIF4E and thus the ability of this regulator to act as a competitive inhibitor. This work identifies the key role of solvent-facing amino acids in 4E-BP1 that are not directly engaged in interactions with eIF4E. These amino acid residues influence the propensity of the natively unfolded binding motif to fold into a conformation, including a stretch of á-helix, that is required for tight binding to eIF4E. In so doing, they contribute to a free energy landscape for 4E-BP1 folding that is poised so that phosphorylation of S65 at the C-terminal end of the helical region can modulate the propensity of folding, and thus regulate the overall free energy of 4E-BP1 binding to eIF4E, over a physiologically significant range. Thus, phosphorylation acts as an intramolecular structural modulator that biases the free energy landscape for the disorder-order transition of 4E-BP1 by destabilizing the á-helix to favor the unfolded form that cannot bind eIF4E. This type of order-disorder regulatory mechanism is likely to be relevant to other intermolecular regulatory phenomena in the cell.
AB - The molecular mechanism underpinning regulation of eukaryotic translation initiation factor eIF4E by 4E-BP1 has remained unclear. We use isothermal calorimetry, circular dichroism, NMR, and computational modeling to analyze how the structure of the eIF4E-binding domain of 4E-BP1 determines its affinity for the dorsal face of eIF4E and thus the ability of this regulator to act as a competitive inhibitor. This work identifies the key role of solvent-facing amino acids in 4E-BP1 that are not directly engaged in interactions with eIF4E. These amino acid residues influence the propensity of the natively unfolded binding motif to fold into a conformation, including a stretch of á-helix, that is required for tight binding to eIF4E. In so doing, they contribute to a free energy landscape for 4E-BP1 folding that is poised so that phosphorylation of S65 at the C-terminal end of the helical region can modulate the propensity of folding, and thus regulate the overall free energy of 4E-BP1 binding to eIF4E, over a physiologically significant range. Thus, phosphorylation acts as an intramolecular structural modulator that biases the free energy landscape for the disorder-order transition of 4E-BP1 by destabilizing the á-helix to favor the unfolded form that cannot bind eIF4E. This type of order-disorder regulatory mechanism is likely to be relevant to other intermolecular regulatory phenomena in the cell.
KW - Conformational change
KW - Intrinsically unstructured proteins
KW - Posttranscriptional control
KW - mRNA cap binding
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U2 - 10.1073/pnas.1008242107
DO - 10.1073/pnas.1008242107
M3 - Article
C2 - 20880835
AN - SCOPUS:78049268257
SN - 0027-8424
VL - 107
SP - 17627
EP - 17632
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 41
ER -