TY - JOUR
T1 - The binding mechanism of eIF2β with its partner proteins, eIF5 and eIF2Bε
AU - Gai, Zuoqi
AU - Kitagawa, Yumie
AU - Tanaka, Yoshikazu
AU - Shimizu, Nobutaka
AU - Komoda, Keisuke
AU - Tanaka, Isao
AU - Yao, Min
N1 - Funding Information:
We thank Dr Masaaki Sokabe, Dr Toyoyuki Ose and Dr Takashi Matsui for their assistance in the current research. We also thank the staff of beamline BL45, SPring-8 of Japan for their help with SAXS data measurements. Zuoqi Gai was supported by the International Graduate Program for Research Pioneers in Life Sciences (IGP-RPLS). This work was supported by Grant-in-aid for Scientific Research (B) (No. 21370041 to M. Y) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
PY - 2012/7/6
Y1 - 2012/7/6
N2 - The eukaryotic translation initiation factor eIF2 delivers Met-tRNAiMet to the ribosomal small subunit in GTP-bound form associated with eIF1, eIF1A, eIF3 and eIF5, and dissociates together with eIF5 as eIF5-eIF2-GDP complex from the ribosomal small subunit after formation of start codon-anticodon base pairing between Met-tRNAiMet and mRNA. The inactive form eIF2-GDP is then exchanged for the active form eIF2-GTP by eIF2B for further initiation cycle. Previous studies showed that the C-terminal domains of eIF5 (eIF5-CTD) and eIF2Bε (eIF2Bε-CTD) have a common eIF2β-binding site for interacting with an N-terminal region of eIF2β (eIF2β-NTD). Here we have reconstructed the complexes of (eIF5-CTD)-(eIF2β-NTD) and (eIF2Bε-CTD)-(eIF2β-NTD) i. n vitro, and investigated binding mechanism by circular dichroism spectroscopy and small angle X-ray scattering in solution. The results showed the conformation of eIF2β-NTD was changed when bound to partner proteins, whereas the structures of eIF5-CTD and eIF2Bε-CTD were similar in both isolated and complex states. We propose that eIF2β-NTD works as an intrinsically disordered domain which is disorder in the isolated state, but folds into a definite structure when bound to its partner proteins. Such flexibility of eIF2β-NTD is expected to be responsible for its binding capability.
AB - The eukaryotic translation initiation factor eIF2 delivers Met-tRNAiMet to the ribosomal small subunit in GTP-bound form associated with eIF1, eIF1A, eIF3 and eIF5, and dissociates together with eIF5 as eIF5-eIF2-GDP complex from the ribosomal small subunit after formation of start codon-anticodon base pairing between Met-tRNAiMet and mRNA. The inactive form eIF2-GDP is then exchanged for the active form eIF2-GTP by eIF2B for further initiation cycle. Previous studies showed that the C-terminal domains of eIF5 (eIF5-CTD) and eIF2Bε (eIF2Bε-CTD) have a common eIF2β-binding site for interacting with an N-terminal region of eIF2β (eIF2β-NTD). Here we have reconstructed the complexes of (eIF5-CTD)-(eIF2β-NTD) and (eIF2Bε-CTD)-(eIF2β-NTD) i. n vitro, and investigated binding mechanism by circular dichroism spectroscopy and small angle X-ray scattering in solution. The results showed the conformation of eIF2β-NTD was changed when bound to partner proteins, whereas the structures of eIF5-CTD and eIF2Bε-CTD were similar in both isolated and complex states. We propose that eIF2β-NTD works as an intrinsically disordered domain which is disorder in the isolated state, but folds into a definite structure when bound to its partner proteins. Such flexibility of eIF2β-NTD is expected to be responsible for its binding capability.
KW - EIF2
KW - EIF2B
KW - EIF5
KW - Intrinsically disordered domain
KW - Translation initiation
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U2 - 10.1016/j.bbrc.2012.05.155
DO - 10.1016/j.bbrc.2012.05.155
M3 - Article
C2 - 22683627
AN - SCOPUS:84863304649
VL - 423
SP - 515
EP - 519
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
IS - 3
ER -