Although the central α-helical Y(X)4LΦ motif (X, variable amino acid; Φ, hydrophobic amino acid) of the translational regulator 4E-BP [eIF (eukaryotic initiation factor) 4E-binding protein] is the core binding region for the mRNA cap-binding protein eIF4E, the functions of its N- and C-terminal flexible regions for interaction with eIF4E remain to be elucidated. To identify the role for the C-terminal region in such an interaction, the binding features of full-length and sequential C-terminal deletion mutants of 4E-BPn (n=1–3) subtypes were investigated by SPR (surface plasmon resonance) analysis and ITC (isothermal titration calorimetry). Consequently, the conserved PGVTS/T motif within the C-terminal region was shown to act as the second binding region and to play an important role in the tight binding to eIF4E. The 4E-BP subtypes increased the association constant with eIF4E by approximately 1000-fold in the presence of this conserved region compared with that in the absence of this region. The sequential deletion of this conserved region in 4E-BP1 showed that deletion of Val81 leads to a considerable decrease in the binding ability of 4E-BP. Molecular dynamics simulation suggested that the conserved PGVTS/T region functions as a kind of paste, adhering the root of both the eIF4E N-terminal and 4E-BP C-terminal flexible regions through a hydrophobic interaction, where valine is located at the crossing position of both flexible regions. It is concluded that the conserved PGVTS/T motif within the flexible C-terminus of 4E-BP plays an auxiliary, but indispensable, role in strengthening the binding of eIF4E to the core Y(X)4LΦ motif.
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Research Article|
December 14 2011
A conserved motif within the flexible C-terminus of the translational regulator 4E-BP is required for tight binding to the mRNA cap-binding protein eIF4E
Keum Soon Paku;
Keum Soon Paku
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Yu Umenaga;
Yu Umenaga
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Tsunego Usui;
Tsunego Usui
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Ai Fukuyo;
Ai Fukuyo
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Atsuo Mizuno;
Atsuo Mizuno
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Yasuko In;
Yasuko In
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Toshimasa Ishida;
Toshimasa Ishida
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Koji Tomoo
Koji Tomoo
1
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
1To whom correspondence should be addressed (e-mail tomoo@gly.oups.ac.jp).
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Publisher: Portland Press Ltd
Received:
September 13 2010
Revision Received:
August 30 2011
Accepted:
September 13 2011
Accepted Manuscript online:
September 13 2011
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2012 Biochemical Society
2012
Biochem J (2012) 441 (1): 237–245.
Article history
Received:
September 13 2010
Revision Received:
August 30 2011
Accepted:
September 13 2011
Accepted Manuscript online:
September 13 2011
Citation
Keum Soon Paku, Yu Umenaga, Tsunego Usui, Ai Fukuyo, Atsuo Mizuno, Yasuko In, Toshimasa Ishida, Koji Tomoo; A conserved motif within the flexible C-terminus of the translational regulator 4E-BP is required for tight binding to the mRNA cap-binding protein eIF4E. Biochem J 1 January 2012; 441 (1): 237–245. doi: https://doi.org/10.1042/BJ20101481
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