scholarly journals RNA-binding activity of translation initiation factor eIF4G1 from Saccharomyces cerevisiae

RNA ◽  
2003 ◽  
Vol 9 (7) ◽  
pp. 871-880 ◽  
Author(s):  
C. BERSET
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Translation Initiation ◽  
Rna Binding ◽  
Binding Activity ◽  
Translation Initiation Factor ◽  
Initiation Factor

scholarly journals Requirement of RNA Binding of Mammalian Eukaryotic Translation Initiation Factor 4GI (eIF4GI) for Efficient Interaction of eIF4E with the mRNA Cap

2008 ◽  
Vol 29 (6) ◽  
pp. 1661-1669 ◽  
Author(s):  
Akiko Yanagiya ◽  
Yuri V. Svitkin ◽  
Shoichiro Shibata ◽  
Satoshi Mikami ◽  
Hiroaki Imataka ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Rna Binding ◽  
Binding Activity ◽  
Translation Initiation Factor ◽  
Scaffolding Protein ◽  
Initiation Factor ◽  
Rna Recognition Motif ◽  
Eukaryotic Translation Initiation Factor ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation

ABSTRACT Eukaryotic mRNAs possess a 5′-terminal cap structure (cap), m7GpppN, which facilitates ribosome binding. The cap is bound by eukaryotic translation initiation factor 4F (eIF4F), which is composed of eIF4E, eIF4G, and eIF4A. eIF4E is the cap-binding subunit, eIF4A is an RNA helicase, and eIF4G is a scaffolding protein that bridges between the mRNA and ribosome. eIF4G contains an RNA-binding domain, which was suggested to stimulate eIF4E interaction with the cap in mammals. In Saccharomyces cerevisiae, however, such an effect was not observed. Here, we used recombinant proteins to reconstitute the cap binding of the mammalian eIF4E-eIF4GI complex to investigate the importance of the RNA-binding region of eIF4GI for cap interaction with eIF4E. We demonstrate that chemical cross-linking of eIF4E to the cap structure is dramatically enhanced by eIF4GI fragments possessing RNA-binding activity. Furthermore, the fusion of RNA recognition motif 1 (RRM1) of the La autoantigen to the N terminus of eIF4GI confers enhanced association between the cap structure and eIF4E. These results demonstrate that eIF4GI serves to anchor eIF4E to the mRNA and enhance its interaction with the cap structure.

scholarly journals Translation initiation factor 4A from Saccharomyces cerevisiae: analysis of residues conserved in the D-E-A-D family of RNA helicases.

1991 ◽  
Vol 11 (7) ◽  
pp. 3463-3471 ◽  
Author(s):  
S R Schmid ◽  
P Linder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Clear Correlation ◽  
Temperature Sensitive ◽  
Rna Helicases ◽  
Initiation Of Translation

The eukaryotic translation initiation factor 4A (eIF-4A) possesses an in vitro helicase activity that allows the unwinding of double-stranded RNA. This activity is dependent on ATP hydrolysis and the presence of another translation initiation factor, eIF-4B. These two initiation factors are thought to unwind mRNA secondary structures in preparation for ribosome binding and initiation of translation. To further characterize the function of eIF-4A in cellular translation and its interaction with other elements of the translation machinery, we have isolated mutations in the TIF1 and TIF2 genes encoding eIF-4A in Saccharomyces cerevisiae. We show that three highly conserved domains of the D-E-A-D protein family, encoding eIF-4A and other RNA helicases, are essential for protein function. Only in rare cases could we make a conservative substitution without affecting cell growth. The mutants show a clear correlation between their growth and in vivo translation rates. One mutation that results in a temperature-sensitive phenotype reveals an immediate decrease in translation activity following a shift to the nonpermissive temperature. These in vivo results confirm previous in vitro data demonstrating an absolute dependence of translation on the TIF1 and TIF2 gene products.

scholarly journals Fal1p is an essential DEAD-box protein involved in 40S-ribosomal-subunit biogenesis in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (12) ◽  
pp. 7283-7294 ◽  
Author(s):  
D Kressler ◽  
J de la Cruz ◽  
M Rojo ◽  
P Linder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Translation Initiation ◽  
18S Rrna ◽  
Amino Acid Level ◽  
Ribosomal Subunit ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Northern Hybridization ◽  
Ribosomal Subunits ◽  
Dead Box

A previously uncharacterized Saccharomyces cerevisiae gene, FAL1, was found by sequence comparison as a homolog of the eukaryotic translation initiation factor 4A (eIF4A). Fal1p has 55% identity and 73% similarity on the amino acid level to yeast eIF4A, the prototype of ATP-dependent RNA helicases of the DEAD-box protein family. Although clearly grouped in the eIF4A subfamily, the essential Fal1p displays a different subcellular function and localization. An HA epitope-tagged Fal1p is localized predominantly in the nucleolus. Polysome analyses in a temperature-sensitive fal1-1 mutant and a Fal1p-depleted strain reveal a decrease in the number of 40S ribosomal subunits. Furthermore, these strains are hypersensitive to the aminoglycoside antibiotics paromomycin and neomycin. Pulse-chase labeling of pre-rRNA and steady-state-level analysis of pre-rRNAs and mature rRNAs by Northern hybridization and primer extension in the Fal1p-depleted strain show that Fal1p is required for pre-rRNA processing at sites A0, A1, and A2. Consequently, depletion of Fal1p leads to decreased 18S rRNA levels and to an overall deficit in 40S ribosomal subunits. Together, these results implicate Fal1p in the 18S rRNA maturation pathway rather than in translation initiation.

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 A Novel Function of the MA-3 Domains in Transformation and Translation Suppressor Pdcd4 Is Essential for Its Binding to Eukaryotic Translation Initiation Factor 4A

2004 ◽  
Vol 24 (9) ◽  
pp. 3894-3906 ◽  
Author(s):  
Hsin-Sheng Yang ◽  
Myung-Haing Cho ◽  
Halina Zakowicz ◽  
Glenn Hegamyer ◽  
Nahum Sonenberg ◽  
...  
Keyword(s):  
Amino Acid ◽  
Translation Initiation ◽  
Binding Activity ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Amino Acid Residues ◽  
Eukaryotic Translation Initiation Factor ◽  
Stem Loop ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation

ABSTRACT Αn α-helical MA-3 domain appears in several translation initiation factors, including human eukaryotic translation initiation factor 4G (eIF4G) and DAP-5/NAT1/p97, as well as in the tumor suppressor Pdcd4. The function of the MA-3 domain is, however, unknown. C-terminal eIF4G (eIG4Gc) contains an MA-3 domain that is located within the eIF4A-binding region, suggesting a role for eIF4A binding. Interestingly, C-terminal DAP-5/NAT1/p97 contains an MA-3 domain, but it does not bind to eIF4A. Mutation of amino acid residues conserved between Pdcd4 and eIF4Gc but not in DAP-5/NAT1/p97 to the amino acid residues found in the DAP-5/NAT1/p97 indicates that some of these amino acid residues within the MA-3 domain are critical for eIF4A-binding activity. Six Pdcd4 mutants (Pdcd4E249K, Pdcd4D253A, Pdcd4D414K, Pdcd4D418A, Pdcd4E249K,D414K, and Pdcd4D253A,D418A) lost >90% eIF4A-binding activity. Mutation of the corresponding amino acid residues in the eIF4Gc also produced similar results, as seen for Pdcd4. These results demonstrate that the MA-3 domain is important for eIF4A binding and explain the ability of Pdcd4 or eIF4Gc but not DAP-5/NAT1/p97 to bind to eIF4A. Competition experiments indicate that Pdcd4 prevents ca. 60 to 70% of eIF4A binding to eIF4Gc at a Pdcd4/eIF4A ratio of 1:1, but mutants Pdcd4D253A and Pdcd4D253A,D418A do not. Translation of stem-loop structured mRNA is susceptible to inhibition by wild-type Pdcd4 but not by Pdcd4D253A, Pdcd4D418A, or Pdcd4D235A,D418A. Together, these results indicate that not only binding to eIF4A but also prevention of eIF4A binding to the MA-3 domain of eIF4Gc contributes to the mechanism by which Pdcd4 inhibits translation.

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