scholarly journals Complex Formation between Potyvirus VPg and Translation Eukaryotic Initiation Factor 4E Correlates with Virus Infectivity

2000 ◽  
Vol 74 (17) ◽  
pp. 7730-7737 ◽  
Author(s):  
Simon Léonard ◽  
Daniel Plante ◽  
Sylvie Wittmann ◽  
Nicole Daigneault ◽  
Marc G. Fortin ◽  
...  
Keyword(s):  
Complex Formation ◽  
Aspartic Acid ◽  
Biological Significance ◽  
Virus Production ◽  
Initiation Factor ◽  
Critical Element ◽  
Virus Infectivity ◽  
Eukaryotic Initiation Factor ◽  
Interaction Domain ◽  
Initiation Of Translation

ABSTRACT The interaction between the viral protein linked to the genome (VPg) of turnip mosaic potyvirus (TuMV) and the translation eukaryotic initiation factor eIF(iso)4E of Arabidopsis thaliana has previously been reported. eIF(iso)4E binds the cap structure (m7GpppN, where N is any nucleotide) of mRNAs and has an important role in the regulation in the initiation of translation. In the present study, it was shown that not only did VPg bind eIF(iso)4E but it also interacted with the eIF4E isomer of A. thalianaas well as with eIF(iso)4E of Triticum aestivum (wheat). The interaction domain on VPg was mapped to a stretch of 35 amino acids, and substitution of an aspartic acid residue found within this region completely abolished the interaction. The cap analogue m7GTP, but not GTP, inhibited VPg-eIF(iso)4E complex formation, suggesting that VPg and cellular mRNAs compete for eIF(iso)4E binding. The biological significance of this interaction was investigated. Brassica perviridis plants were infected with a TuMV infectious cDNA (p35Tunos) and p35TuD77N, a mutant which contained the aspartic acid substitution in the VPg domain that abolished the interaction with eIF(iso)4E. After 20 days, plants bombarded with p35Tunos showed viral symptoms, while plants bombarded with p35TuD77N remained symptomless. These results suggest that VPg-eIF(iso)4E interaction is a critical element for virus production.

scholarly journals Physical Association of Eukaryotic Initiation Factor 4G (eIF4G) with eIF4A Strongly Enhances Binding of eIF4G to the Internal Ribosomal Entry Site of Encephalomyocarditis Virus and Is Required for Internal Initiation of Translation

2000 ◽  
Vol 20 (16) ◽  
pp. 6019-6029 ◽  
Author(s):  
Ivan B. Lomakin ◽  
Christopher U. T. Hellen ◽  
Tatyana V. Pestova
Keyword(s):  
Complex Formation ◽  
Internal Ribosomal Entry Site ◽  
Encephalomyocarditis Virus ◽  
Initiation Factor ◽  
Rna Recognition Motif ◽  
Eukaryotic Initiation Factor ◽  
Entry Site ◽  
Amino Terminal ◽  
Initiation Of Translation ◽  
Ribosomal Entry

ABSTRACT Mammalian eukaryotic initiation factor 4GI (eIF4GI) may be divided into three similarly sized regions. The central region (amino acids [aa] 613 to 1090) binds eIF3, eIF4A, and the encephalomyocarditis virus (EMCV) internal ribosomal entry site (IRES) and mediates initiation on this RNA. We identified the regions of eIF4GI that are responsible for its specific interaction with the IRES and that are required to mediate 48S complex formation on the IRES in vitro. Mutational analysis demarcated the IRES binding fragment of eIF4GI (aa 746 to 949) and indicated that it does not resemble an RNA recognition motif (RRM)-like domain. An additional amino-terminal sequence (aa 722 to 746) was required for binding eIF4A and for 48S complex formation. eIF4GI bound the EMCV IRES and β-globin mRNA with similar affinities, but association with eIF4A increased its affinity for the EMCV IRES (but not β-globin RNA) by 2 orders of magnitude. On the other hand, eIF4GI mutants with defects in binding eIF4A were defective in mediating 48S complex formation even if they bound the IRES normally. These data indicate that the eIF4G-eIF4A complex, rather than eIF4G alone, is required for specific high-affinity binding to the EMCV IRES and for internal ribosomal entry on this RNA.

scholarly journals A region rich in aspartic acid, arginine, tyrosine, and glycine (DRYG) mediates eukaryotic initiation factor 4B (eIF4B) self-association and interaction with eIF3.

1996 ◽  
Vol 16 (10) ◽  
pp. 5328-5334 ◽  
Author(s):  
N Méthot ◽  
M S Song ◽  
N Sonenberg
Keyword(s):  
Aspartic Acid ◽  
Ribosomal Subunit ◽  
Direct Interaction ◽  
Initiation Factor ◽  
Eukaryotic Initiation Factor ◽  
Ribosome Binding ◽  
Initiation Factors ◽  
Self Association

The binding of mRNA to the ribosome is mediated by eukaryotic initiation factors eukaryotic initiation factor 4F (eIF4F), eIF4B, eIF4A, and eIF3, eIF4F binds to the mRNA cap structure and, in combination with eIF4B, is believed to unwind the secondary structure in the 5' untranslated region to facilitate ribosome binding. eIF3 associates with the 40S ribosomal subunit prior to mRNA binding. eIF4B copurifies with eIF3 and eIF4F through several purification steps, suggesting the involvement of a multisubunit complex during translation initiation. To understand the mechanism by which eIF4B promotes 40S ribosome binding to the mRNA, we studied its interactions with partner proteins by using a filter overlay (protein-protein [far Western]) assay and the two-hybrid system. In this report, we show that eIF4B self-associates and also interacts directly with the p170 subunit of eIF3. A region rich in aspartic acid, arginine, tyrosine, and glycine, termed the DRYG domain, is sufficient for self-association of eIF4B, both in vitro and in vivo, and for interaction with the p170 subunit of eIF3. These experiments suggest that eIF4B participates in mRNA-ribosome binding by acting as an intermediary between the mRNA and eIF3, via a direct interaction with the p170 subunit of eIF3.

scholarly journals Granzyme B Inhibits Vaccinia Virus Production through Proteolytic Cleavage of Eukaryotic Initiation Factor 4 Gamma 3

2011 ◽  
Vol 7 (12) ◽  
pp. e1002447 ◽  
Author(s):  
Marcelo Marcet-Palacios ◽  
Brenda Lee Duggan ◽  
Irene Shostak ◽  
Michele Barry ◽  
Tracy Geskes ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Granzyme B ◽  
Virus Production ◽  
Proteolytic Cleavage ◽  
Initiation Factor ◽  
Eukaryotic Initiation Factor

scholarly journals Cleavage of Human Cytomegalovirus Protease pUL80a at Internal and Cryptic Sites Is Not Essential but Enhances Infectivity

2005 ◽  
Vol 79 (20) ◽  
pp. 12961-12968 ◽  
Author(s):  
Amy N. Loveland ◽  
Chee-Kai Chan ◽  
Edward J. Brignole ◽  
Wade Gibson
Keyword(s):  
Human Cytomegalovirus ◽  
Cleavage Site ◽  
Biological Significance ◽  
Virus Production ◽  
Mutant Virus ◽  
Wild Type Virus ◽  
Virus Infectivity ◽  
Type Virus ◽  
Wild Type ◽  
Biological Importance

ABSTRACT The cytomegalovirus (CMV) maturational protease, assemblin, contains an “internal” (I) cleavage site absent from its homologs in other herpesviruses. Blocking this site for cleavage did not prevent replication of the resulting I− mutant virus. However, cells infected with the I− virus showed increased amounts of a fragment produced by cleavage at the nearby “cryptic” (C) site, suggesting that its replication may bypass the I-site block by using the C site as an alternate cleavage pathway. To test this and further examine the biological importance of these cleavages, we constructed two additional virus mutants—one blocked for C-site cleavage and another blocked for both I- and C-site cleavage. Infectivity comparisons with the parental wild-type virus showed that the I− mutant was the least affected for virus production, whereas infectivity of the C− mutant was reduced by ≈40% and when both sites were blocked virus infectivity was reduced by nearly 90%, providing the first evidence that these cleavages have biological significance. We also present and discuss evidence suggesting that I-site cleavage destabilizes assemblin and its fragments, whereas C-site cleavage does not.

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