Further Biochemical Characterization of Rabbit Reticulocyte eIF-4B

Hughes, Diane L.; Dever, Thomas E.; Merrick, William C.

doi:10.1006/abbi.1993.1149

Cited by 11 publications

(13 citation statements)

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“…4) indicates that these two proteins interact physically or functionally in yeast. This is consistent with previously reported genetic interactions between eIF4A and eIF4B in yeast (Coppolecchia et al 1993;de la Cruz et al 1997) and RNA-dependent physical interactions between mammalian eIF4A and eIF4B (Grifo et al 1983;Hughes et al 1993;Rozovsky et al 2008;Nielsen et al 2011), as well as interactions between the mammalian eIF4B homolog eIF4H and eIF4A (Marintchev et al 2009). Interaction between eIF4B and eIF4A could be responsible for the low K 1/2 of eIF4B in mRNA recruitment assays relative to its K d for 40S subunits.…”

Section: Discussionsupporting

confidence: 92%

“…yeIF4B binds directly to the 40S subunit and ssRNA Previous studies suggested that mammalian eIF4B binds to ssRNA and 18S rRNA (Milburn et al 1990;Hughes et al 1993;Naranda et al 1994;Methot et al 1996a,b), and that yeIF4B also binds ssRNA (Altmann et al 1995;Niederberger et al 1998). We developed assays to quantify binding of purified yeIF4B to ssRNA and purified ribosomal subunits in vitro.…”

Section: Resultsmentioning

confidence: 99%

“…Previous work had suggested that mammalian eIF4B interacts with ribosomes in vivo (Hughes et al 1993;Naranda et al 1994) and that its RRM binds specifically to 18S rRNA (Methot et al 1996a). Our data demonstrate that yeIF4B binds specifically and tightly to the 40S ribosomal subunit, although this activity does not require the RRM domain and is instead mediated by the NTD and 7-repeats.…”

Section: Yeif4b Is a 40s Ribosomal Subunit-binding Proteinmentioning

confidence: 99%

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Yeast eIF4B binds to the head of the 40S ribosomal subunit and promotes mRNA recruitment through its N-terminal and internal repeat domains

Walker

Zhou

Mitchell

et al. 2012

RNA

154

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Eukaryotic translation initiation factor (eIF)4B stimulates recruitment of mRNA to the 43S ribosomal pre-initiation complex (PIC). Yeast eIF4B (yeIF4B), shown previously to bind single-stranded (ss) RNA, consists of an N-terminal domain (NTD), predicted to be unstructured in solution; an RNA-recognition motif (RRM); an unusual domain comprised of seven imperfect repeats of 26 amino acids; and a C-terminal domain. Although the mechanism of yeIF4B action has remained obscure, most models have suggested central roles for its RRM and ssRNA-binding activity. We have dissected the functions of yeIF4B's domains and show that the RRM and its ssRNA-binding activity are dispensable in vitro and in vivo. Instead, our data indicate that the 7-repeats and NTD are the most critical domains, which mediate binding of yeIF4B to the head of the 40S ribosomal subunit via interaction with Rps20. This interaction induces structural changes in the ribosome's mRNA entry channel that could facilitate mRNA loading. We also show that yeIF4B strongly promotes productive interaction of eIF4A with the 43S•mRNA PIC in a manner required for efficient mRNA recruitment.

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Section: Discussionsupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Yeif4b Is a 40s Ribosomal Subunit-binding Proteinmentioning

confidence: 99%

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Yeast eIF4B binds to the head of the 40S ribosomal subunit and promotes mRNA recruitment through its N-terminal and internal repeat domains

Walker

Zhou

Mitchell

et al. 2012

RNA

154

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“…6B, upper panel). Only minute amounts of eIF4B were detected in the lower fractions of the gradient, possibly due to the ability of eIF4B to weakly interact even with purified ribosomes in the absence of mRNA (15). When 10 g of cellular poly(A) ϩ RNA was added, no change in the detection of eIF4B throughout the gradient fractions was observed (Fig.…”

Section: Binding Of Eif4b To the Poliovirus Ires Is Strong Compared Wmentioning

confidence: 94%

Interaction of Translation Initiation Factor eIF4B with the Poliovirus Internal Ribosome Entry Site

Ochs¹,

Saleh²,

Bassili³

et al. 2002

J Virol

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Poliovirus translation is initiated at the internal ribosome entry site (IRES). Most likely involving the action of standard initiation factors, this highly structured cis element in the 5 noncoding region of the viral RNA guides the ribosome to an internal silent AUG. The actual start codon for viral protein synthesis further downstream is then reached by ribosomal scanning. In this study we show that two of the secondary structure elements of the poliovirus IRES, domain V and, to a minor extent, domain VI, are the determinants for binding of the eukaryotic initiation factor eIF4B. Several mutations in domain V which are known to greatly affect poliovirus growth also seriously impair the binding of eIF4B. The interaction of eIF4B with the IRES is not dependent on the presence of the polypyrimidine tract-binding protein, which also binds to the poliovirus IRES. In contrast to its weak interaction with cellular mRNAs, eIF4B remains tightly associated with the poliovirus IRES during the formation of complete 80S ribosomes. Binding of eIF4B to the IRES is energy dependent, and binding of the small ribosomal subunit to the IRES requires the previous energy-dependent association of initiation factors with the IRES. These results indicate that the interaction of eIF4B with the 3 region of the poliovirus IRES may be directly involved in translation initiation.When poliovirus, the paradigm of the family of picornaviruses, infects a susceptible cell, the positive-strand viral RNA can be used directly for translation of the viral polyprotein. In contrast to normal cellular mRNAs, translation of the picornaviral RNA is facilitated by an internal region of the viral RNA, the internal ribosome entry site (IRES). This strategy of internal initiation allows some picornaviruses to take advantage of the obvious opportunity and shut down the cap-dependent cellular translation, while synthesis of the picornaviral polyprotein is initiated cap independently from the IRES element (for an overview, see reference 3).Picornavirus IRES elements are large cis-acting RNA regions that guide ribosomes to an internal site of the viral RNA (17, 37, 51). They are classified into three groups according to their primary and secondary structures: the type I elements of the enterovirus-rhinovirus group (including poliovirus), the type II elements of the cardiovirus-aphthovirus group, and the type III element of hepatitis A virus (HAV). The IRES elements consist of highly conserved RNA secondary structure domains and have a characteristic oligopyrimidine tract followed by a conserved AUG triplet at their 3Ј borders (8,42,44). In poliovirus, this AUG is important but silent for translation, while the actual initiation codon further downstream is reached by ribosomal scanning (20,22,25,39). The small ribosomal subunit is guided to a starting window (43) containing the conserved AUG triplet, most likely by the action of initiation factors. In addition to the standard initiation factors, picornavirus IRES elements recruit other cellular RNA-binding prot...

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“…It is absolutely required for mRNA binding to ribosomes (6,60) and considerably stimulates the helicase activity of eIF-4A and eIF-4F (31,50). Recently, eIF-4B has been shown to possess a ribosome-dependent ATPase activity (24). Another possible function of eIF-4B is the recycling of the eIF-4E component of eIF-4F (46).…”

mentioning

confidence: 99%

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

Méthot¹,

Pause²,

Hershey³

et al. 1994

Mol. Cell. Biol.

101

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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 carboxyterminal RNA-binding region of eIF-4B is essential for eIF-4B function and is distinct from the RNP-CS/RRM.

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Further Biochemical Characterization of Rabbit Reticulocyte eIF-4B

Cited by 11 publications

References 0 publications

Yeast eIF4B binds to the head of the 40S ribosomal subunit and promotes mRNA recruitment through its N-terminal and internal repeat domains

Yeast eIF4B binds to the head of the 40S ribosomal subunit and promotes mRNA recruitment through its N-terminal and internal repeat domains

Interaction of Translation Initiation Factor eIF4B with the Poliovirus Internal Ribosome Entry Site

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

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