Abstract 4447: Structural basis of human translation initiation factor eIF4G-enhanced helicase activity of eIF4A in tumorigenesis

2018 ◽  
Author(s):  
Puja Singh ◽  
Hanyong Chen ◽  
Young-In Chi ◽  
Junxuan Lu ◽  
Zigang Dong ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Structural Basis ◽  
Helicase Activity

scholarly journals The translation initiation factor eIF-4B contains an RNA-binding region that is distinct and independent from its ribonucleoprotein consensus sequence.

1994 ◽  
Vol 14 (4) ◽  
pp. 2307-2316 ◽  
Author(s):  
N Méthot ◽  
A Pause ◽  
J W Hershey ◽  
N Sonenberg
Keyword(s):  
Translation Initiation ◽  
Rna Binding ◽  
Consensus Sequence ◽  
Point Mutations ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Rna Recognition Motif ◽  
Helicase Activity ◽  
Binding Region ◽  
Stimulation Of

eIF-4B is a eukaryotic translation initiation factor that is required for the binding of ribosomes to mRNAs and the stimulation of the helicase activity of eIF-4A. It is an RNA-binding protein that contains a ribonucleoprotein consensus sequence (RNP-CS)/RNA recognition motif (RRM). We examined the effects of deletions and point mutations on the ability of eIF-4B to bind a random RNA, to cooperate with eIF-4A in RNA binding, and to enhance the helicase activity of eIF-4A. We report here that the RNP-CS/RRM alone is not sufficient for eIF-4B binding to RNA and that an RNA-binding region, located between amino acids 367 and 423, is the major contributor to RNA binding. Deletions which remove this region abolish the ability of eIF-4B to cooperate with eIF-4A in RNA binding and the ability to stimulate the helicase activity of eIF-4A. Point mutations in the RNP-CS/RRM had no effect on the ability of eIF-4B to cooperate with eIF-4A in RNA binding but significantly reduced the stimulation of eIF-4A helicase activity. Our results indicate that the carboxy-terminal RNA-binding region of eIF-4B is essential for eIF-4B function and is distinct from the RNP-CS/RRM.

scholarly journals Structural basis for the inhibition of translation through eIF2α phosphorylation

2018 ◽  
Author(s):  
Yuliya Gordiyenko ◽  
José Luis Llácer ◽  
Venki Ramakrishnan
Keyword(s):  
Translation Initiation ◽  
Ternary Complex ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Cells ◽  
Structural Basis ◽  
Eif2α Phosphorylation ◽  
Α Subunits ◽  
Initiation Factor Eif2 ◽  
Phosphate Groups

AbstractOne of the responses to stress by eukaryotic cells is the down-regulation of protein synthesis by phosphorylation of translation initiation factor eIF2. Phosphorylation results in low availability of the eIF2 ternary complex (eIF2-GTP-tRNAi) by affecting its interaction with its GTP-GDP exchange factor eIF2B. We have determined the cryo-EM structure of eIF2B in complex with phosphorylated eIF2 at an overall resolution of 4.15 Å. Two eIF2 molecules bind opposite sides of an eIF2B hetero-decamer through eIF2α-D1, which contains the phosphorylated Ser51. eIF2α-D1 is mainly inserted between the N-terminal helix bundle domains of δ and α subunits of eIF2B. Phosphorylation of Ser51 enhances binding to eIF2B through direct interactions of phosphate groups with residues in eIF2Bα and indirectly by inducing contacts of eIF2α helix 58-63 with eIF2Bδ leading to a competition with Met-tRNAi.

scholarly journals A novel inhibitor stabilizes the inactive conformation of MAPK-interacting kinase 1

2018 ◽  
Vol 74 (3) ◽  
pp. 156-160 ◽  
Author(s):  
Yumi Matsui ◽  
Isao Yasumatsu ◽  
Ken-ichi Yoshida ◽  
Shin Iimura ◽  
Yutaka Ikeno ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Translation Initiation ◽  
Kinase Activity ◽  
Translation Initiation Factor ◽  
Mitogen Activated Protein Kinase ◽  
Initiation Factor ◽  
Structural Basis ◽  
Eukaryotic Translation ◽  
Mitogen Activated Protein ◽  
Eukaryotic Translation Initiation

Mitogen-activated protein kinase (MAPK)-interacting kinases 1 (Mnk1) and 2 (Mnk2) modulate translation initiation through the phosphorylation of eukaryotic translation initiation factor 4E, which promotes tumorigenesis. However, Mnk1 and Mnk2 are dispensable in normal cells, suggesting that the inhibition of Mnk1 and Mnk2 could be effective in cancer therapy. To provide a structural basis for Mnk1 inhibition, a novel Mnk1 inhibitor was discovered and the crystal structure of Mnk1 in complex with this inhibitor was determined. The crystal structure revealed that the inhibitor binds to the autoinhibited state of Mnk1, stabilizing the Mnk-specific DFD motif in the DFD-out conformation, thus preventing Mnk1 from switching to the active conformation and thereby inhibiting the kinase activity. These results provide a valuable platform for the structure-guided design of Mnk1 inhibitors.

The translation initiation factor eIF-4B contains an RNA-binding region that is distinct and independent from its ribonucleoprotein consensus sequence

1994 ◽  
Vol 14 (4) ◽  
pp. 2307-2316
Author(s):  
N Méthot ◽  
A Pause ◽  
J W Hershey ◽  
N Sonenberg
Keyword(s):  
Translation Initiation ◽  
Rna Binding ◽  
Consensus Sequence ◽  
Point Mutations ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Rna Recognition Motif ◽  
Helicase Activity ◽  
Binding Region ◽  
Stimulation Of

eIF-4B is a eukaryotic translation initiation factor that is required for the binding of ribosomes to mRNAs and the stimulation of the helicase activity of eIF-4A. It is an RNA-binding protein that contains a ribonucleoprotein consensus sequence (RNP-CS)/RNA recognition motif (RRM). We examined the effects of deletions and point mutations on the ability of eIF-4B to bind a random RNA, to cooperate with eIF-4A in RNA binding, and to enhance the helicase activity of eIF-4A. We report here that the RNP-CS/RRM alone is not sufficient for eIF-4B binding to RNA and that an RNA-binding region, located between amino acids 367 and 423, is the major contributor to RNA binding. Deletions which remove this region abolish the ability of eIF-4B to cooperate with eIF-4A in RNA binding and the ability to stimulate the helicase activity of eIF-4A. Point mutations in the RNP-CS/RRM had no effect on the ability of eIF-4B to cooperate with eIF-4A in RNA binding but significantly reduced the stimulation of eIF-4A helicase activity. Our results indicate that the carboxy-terminal RNA-binding region of eIF-4B is essential for eIF-4B function and is distinct from the RNP-CS/RRM.

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