SSL1, a suppressor of a HIS4 5'-UTR stem-loop mutation, is essential for translation initiation and affects UV resistance in yeast.

Yoon, Haejin; Miller, Stephen; Pabich, E K; Donahue, Thomas F.

doi:10.1101/gad.6.12b.2463

Cited by 77 publications

(57 citation statements)

References 25 publications

(48 reference statements)

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“…Indirect evidence suggests that this polypeptide may interact with SSL1, a zinc finger-containing protein (63). Both factors, which have been cloned by a genetic screen which selected for suppressors of a translational block of the HIS4 mRNA due to the presence of a stable stem-loop structure in the 5' UTR, were suggested to be novel yeast translation initiation factors.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…One possibility is that Nip1p is a dual function protein with separate roles in protein synthesis and nuclear import. Some other translation factors are known to have multiple functions (62)(63)(64)(65)(66). Finally, we cannot rule out that protein synthesis and nuclear transport are coupled in yeast, and that a defect in protein synthesis translates to a defect in nuclear transport.…”

Section: Cells Depleted Of Nip1p Have a Reduced Rate Of Protein Synthmentioning

confidence: 99%

“…A yeast eIF3 complex was purified on the basis of replacing mammalian eIF3 in an in vitro translation initiation assay (6). This complex contains eight subunits of masses 16,21,29,33,39,62,90, and 135 kDa. The 16-, 39-, 62-, and 90-kDa subunits were identified as Sui1p (7,8), Tif34p (9) Gcd10p (10), and Prt1p (11), respectively.…”

mentioning

confidence: 99%

Nip1p Associates with 40 S Ribosomes and the Prt1p Subunit of Eukaryotic Initiation Factor 3 and Is Required for Efficient Translation Initiation

Greenberg¹,

Phan²,

Gu³

et al. 1998

Journal of Biological Chemistry

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Nip1p is an essential Saccharomyces cerevisiae protein that was identified in a screen for temperature conditional (ts) mutants exhibiting defects in nuclear transport. New results indicate that Nip1p has a primary role in translation initiation. Polysome profiles indicate that cells depleted of Nip1p and nip1-1 cells are defective in translation initiation, a conclusion that is supported by a reduced rate of protein synthesis in Nip1p-depleted cells. Nip1p cosediments with free 40 S ribosomal subunits and polysomal preinitiation complexes, but not with free or elongating 80 S ribosomes or 60 S subunits. Nip1p can be isolated in an about 670-kDa complex containing polyhistidine-tagged Prt1p, a subunit of translation initiation factor 3, by binding to Ni 2؉ -NTA-agarose beads in a manner completely dependent on the tagged form of Prt1p. The nip1-1 ts growth defect was suppressed by the deletion of the ribosomal protein, RPL46. Also, nip1-1 mutant cells are hypersensitive to paromomycin. These results suggest that Nip1p is a subunit of eukaryotic initiation factor 3 required for efficient translation initiation.Translation initiation can be considered to begin with the dissociation of 80 S ribosomes into free 40 S and 60 S subunits which then reassociate with mRNAs in a highly regulated and complex process. Initiation of cap-dependent translation in eukaryotes begins with the binding of a 43 S preinitiation complex to the 5Ј cap of the mRNA. The 43 S ribosome migrates down the mRNA to the translation start site where it is joined by a 60 S ribosomal subunit to complete the assembly of an apparatus capable of accurately forming the first peptide bond. Translation initiation is mediated by at least 10 translation initiation factors, many of which contain multiple subunits that are conserved between yeast and mammals (reviewed in Refs. 1). eIF3 1 is the most complex initiation factor and the one which is least understood with regard to both composition and function. Human eIF3, which is composed of at least nine distinct subunits (2-5), stimulates multiple steps of translation initiation, including the dissociation of 80 S ribosomes, stabilizing tRNA i Met binding to 40 S ribosomal subunits, and binding of mRNA to 40 S subunits (1). A yeast eIF3 complex was purified on the basis of replacing mammalian eIF3 in an in vitro translation initiation assay (6). This complex contains eight subunits of masses 16,21,29,33,39,62, 90, and 135 kDa. The 16-, 39-, 62-, and 90-kDa subunits were identified as Sui1p (7, 8), Tif34p (9) Gcd10p (10), and Prt1p (11), respectively. Yeast Prt1p is 36% identical to the 116-kDa subunit of human eIF3, and Tif34p, a WD repeat protein, is 46% identical to the p36 subunit of human eIF3. Tif34p is required for cell cycle progression and mating as well as translation initiation (12). However, Gcd10p and Sui1p do not show strong similarities to any human eIF3 subunits (13). p33 was shown to interact with Tif34p and Prt1p by two-hybrid analysis and co-immunoprecipitation. It has a RNA-binding domain ...

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“…We tested the ssl1-1 and ssl1-2 ts alleles (Yoon et al, 1992). Double mutants ssl1-1/rat8-2 and ssl1-2/rat8-2 were constructed and growth at different temperatures was compared with growth of the parental strains.…”

Section: Ts Mutations In the Ssl1 Gene Suppress The Rat8 Growth Defecmentioning

confidence: 99%

“…In a search for high-copy suppressors of the rat8 -6 temperature-sensitive allele of DBP5, we identified an N-terminally truncated form of Ssl1p (called Ssl1p-t). Ssl1p is a component of transcription factor IIH (TFIIH), a multiprotein complex that participates in both transcription and excision repair (Yoon et al, 1992;Feaver et al, 1993;Wang et al, 1995). In transcription, TFIIH acts late during initiation and promoter clearance.…”

Section: Introductionmentioning

confidence: 99%

An Early Function during Transcription for the Yeast mRNA Export Factor Dbp5p/Rat8p Suggested by Its Genetic and Physical Interactions with Transcription Factor IIH Components

Estruch

Cole

2003

MBoC

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The yeast DEAD-box protein Dbp5p/Rat8p is an essential factor for mRNA export and shuttles between the nucleus and the cytoplasm. It is concentrated at the cytoplasmic fibrils of the nuclear pore complex where it interacts with several nucleoporins. On the basis of this localization, it has been suggested that it might participate in a terminal step of RNA export, the release from the mRNA of proteins that accompany the mRNA during translocation through nuclear pores. In this report, we present evidence linking Dbp5p to transcription. Two different screens identified genetic interactions between DBP5 and genes involved in early transcription events, initiation and promoter clearance. Mutations of transcription proteins expected to impair transcription act as suppressors of dbp5 mutants, whereas those that may act to increase transcription are synthetically lethal with dbp5 mutations. We also show that growth and mRNA export in dbp5 mutant strains are dependent on the carboxy-terminal domain of the RNA pol II largest subunit. Finally, we show that Dbp5p associates physically with components of transcription factor IIH. Because these interactions affect not only growth but also mRNA export, they are likely to reflect a functional relationship between Dbp5p and the transcription machinery. Together, our results suggest a nuclear role for Dbp5 during the early steps of transcription. INTRODUCTIONIn eukaryotic cells, transcription by RNA polymerase II yields pre-mRNAs that are converted into mRNAs through the RNA-processing events of 5Ј capping, splicing, and 3Ј cleavage/polyadenylation (for reviews, see Proudfoot et al., 2002;Reed and Hurt, 2002). The export of the mRNA to the cytoplasm for translation requires that all of these steps be completed correctly and that certain RNA-binding proteins associate with the mRNA to form heterogeneous ribonucleoprotein particles (hnRNPs) ; for review, see Dreyfuss et al., 2002). Correct and efficient packaging and processing are facilitated by the cotranscriptional recruitment to the RNA of processing factors and RNAbinding proteins (Hirose and Manley, 2000;Lei et al., 2001;Strasser et al., 2002). Although the RNA processing steps are complex and involve many different proteins, it is probable that only a subset of the factors needed for each step associates with RNA polymerase during transcription. The others would likely be recruited once the polymerase-associated factors bound the pre-RNA at appropriate processing sites. Many of these factors are subsequently released as processing steps proceed and are completed, with only a subset remaining with the processed mRNA during the export process.The complex interplay of the events in nuclear mRNA biogenesis is reflected in the observation that defects in export result in defects in processing and defects in processing result in a failure to export the mRNA (Damelin and Silver, 2000;Hilleren et al., 2001;Hillerin and Parker;Jensen et al., 2001b;Hammell et al., 2002). This means that many proteins must function properly for both p...

show abstract

SSL1, a suppressor of a HIS4 5'-UTR stem-loop mutation, is essential for translation initiation and affects UV resistance in yeast.

Cited by 77 publications

References 25 publications

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

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

Nip1p Associates with 40 S Ribosomes and the Prt1p Subunit of Eukaryotic Initiation Factor 3 and Is Required for Efficient Translation Initiation

An Early Function during Transcription for the Yeast mRNA Export Factor Dbp5p/Rat8p Suggested by Its Genetic and Physical Interactions with Transcription Factor IIH Components

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