Mapping of Functional Domains in Eukaryotic Protein Synthesis Initiation Factor 4G (eIF4G) with Picornaviral Proteases

Lamphear, Barry J.; Kirchweger, Regina; Skern, Tim; Rhoads, Robert E.

doi:10.1074/jbc.270.37.21975

Cited by 534 publications

(621 citation statements)

References 65 publications

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“…4). These results suggest that processing of eIF4GI uncouples the cap recognition domain from the ribosome binding and RNA helicase activity provided by eIF3 and eIF4A (Lamphear et al, 1995).…”

Section: Cap-independent Translationmentioning

confidence: 88%

“…reflection of extensive post-translational modifications (Lamphear et al, 1995). However, it rather turned out that the original eIF4GI sequence was incorrect as first evidenced by the fact that homology between eIF4GII and eIF4GI stopped at a putative splice acceptor site suggesting that the published 5' boundaries of eIF4GI contained an intron (Gradi et al, 1998b).…”

Section: Eif4g Synthesis and Clonesmentioning

confidence: 99%

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Conducting the initiation of protein synthesis: the role of eIF4G

Prévot

Darlix

Ohlmann

2003

Biology of the Cell

197

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The eukaryotic initiation factor eIF4G is a large modular protein which serves as a docking site for initiation factors and proteins involved in RNA translation. Together with eIF4E and eIF4A, eIF4G constitutes the eIF4F complex which is a key component in promoting ribosome binding to the mRNA. Thus, the central role of eIF4G in initiation makes it a valid target for events aimed at modulating translation. Such events occur during viral infection by picornaviruses and lentiviruses and result in the hijack of the translational machinery through cleavage of eIF4G. Proteolysis of eIF4G is also mediated by caspases during the onset of apoptosis causing inhibition of protein synthesis. We will review the role of eIF4G and protein partners as well as the cellular and viral events that modulate eIF4G activity in the initiation of translation.

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Section: Cap-independent Translationmentioning

confidence: 88%

Section: Eif4g Synthesis and Clonesmentioning

confidence: 99%

Conducting the initiation of protein synthesis: the role of eIF4G

Prévot

Darlix

Ohlmann

2003

Biology of the Cell

197

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“…Enterovirus proteases, such as CVB3 2A, cleave translation initiation factors, [5][6][7]10,20,[23][24][25][26] leading to shutoff of cellular translation. DAP5, an eIF4G homolog responsible for IRESmediated translation, was found to be cleaved by CVB3 protease 2A.…”

Section: Discussionmentioning

confidence: 99%

Cleavage of DAP5 by coxsackievirus B3 2A protease facilitates viral replication and enhances apoptosis by altering translation of IRES-containing genes

Hanson

Qiu

et al. 2015

Cell Death Differ

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Cleavage of eukaryotic translation initiation factor 4G (eIF4G) by enterovirus proteases during infection leads to the shutoff of cellular cap-dependent translation, but does not affect the initiation of cap-independent translation of mRNAs containing an internal ribosome entry site (IRES). Death-associated protein 5 (DAP5), a structural homolog of eIF4G, is a translation initiation factor specific for IRES-containing mRNAs. Coxsackievirus B3 (CVB3) is a positive single-stranded RNA virus and a primary causal agent of human myocarditis. Its RNA genome harbors an IRES within the 5′-untranslated region and is translated by a cap-independent, IRES-driven mechanism. Previously, we have shown that DAP5 is cleaved during CVB3 infection. However, the protease responsible for cleavage, cleavage site and effects on the translation of target genes during CVB3 infection have not been investigated. In the present study, we demonstrated that viral protease 2A but not 3C is responsible for DAP5 cleavage, generating 45-and 52-kDa N-(DAP5-N) and C-terminal (DAP5-C) fragments, respectively. By site-directed mutagenesis, we found that DAP5 is cleaved at amino acid G434. Upon cleavage, DAP5-N largely translocated to the nucleus at the later time points of infection, whereas the DAP5-C largely remained in the cytoplasm. Overexpression of these DAP5 truncates demonstrated that DAP5-N retained the capability of initiating IRES-driven translation of apoptosis-associated p53, but not the prosurvival Bcl-2 (B-cell lymphoma 2) when compared with the full-length DAP5. Similarly, DAP5-N expression promoted CVB3 replication and progeny release; on the other hand, DAP5-C exerted a dominant-negative effect on cap-dependent translation. Taken together, viral protease 2A-mediated cleavage of DAP5 results in the production of two truncates that exert differential effects on protein translation of the IRES-containing genes, leading to enhanced host cell death. Coxsackievirus B3 (CVB3), a primary cause of viral myocarditis, is associated with sudden, unexpected death, 1 dilated cardiomyopathy and heart failure. 2 The CVB3 genome consists of a single open reading frame, which is translated to a polyprotein, and subsequently processed by viral proteases 2A and 3C. Similar to other picornaviruses, the CVB3 genome is linked to a small viral peptide, Vpg, rather than a 7-methyl guanosine cap structure at its 5′ terminus. Thus, CVB3 RNA is translated by a cap-independent mechanism and is driven by an internal ribosome entry site (IRES) harbored in the 5′ untranslated region (5′-UTR). 3,4 Viral proteases actively suppress multiple host cell activities that help the virus evade host defense mechanisms, promote viral replication and promote host cell apoptosis. For example, enterovirus proteases can cleave eukaryotic translation initiation factors 4GI (eIF4GI) 5-7 and eIF4GII. 8,9 Picornavirus proteases have also been reported to cleave other canonical translation initiation factors in the cap-dependent translation initiation complex, such as eIF5B 10 and ...

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“…This observation implies that the potential second cleavage site within the 3D region, previously assigned as a noncleavage site, added substantially to the complexity of the problem. The neural network trained on several subsets of the picornavirus cleavage sites was then tested for its ability to correctly predict the 2APm cleavage sites in human and rabbit initiation factor eIF-4G (Lamphear et al, 1995). The cleavage site in human eIF-4G gave a high score, whereas prediction of the rabbit 1 3 n " "- eIF-4G cleavage site gave a score just above the threshold of 0.5. dicted correctly, although with low score.…”

Section: Prediction Of 2apm Cleavage Sitesmentioning

confidence: 99%

Cleavage site analysis in picornaviral polyproteins: Discovering cellular targets by neural networks

et al. 1996

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Picornaviral proteinases are responsible for maturation cleavages of the viral polyprotein, but also catalyze the degradation of cellular targets. Using graphical visualization techniques and neural network algorithms, we have investigated the sequence specificity of the two proteinases 2AP" and 3CPm. The cleavage of VPO (giving rise to VP2 and VP4). which is carried out by a so-far unknown proteinase, was also examined. In combination with a novel surface exposure prediction algorithm, our neural network approach successfully distinguishes known cleavage sites from noncleavage sites and yields a more consistent definition of features common to these sites. The method is able to predict experimentally determined cleavage sites in cellular proteins. We present a list of mammalian and other proteins that are predicted to be possible targets for the viral proteinases. Whether these proteins are indeed cleaved awaits experimental verification. Additionally, we report several errors detected in the protein databases.A computer server for prediction of cleavage sites by picornaviral proteinases is publicly available at the e-mail address NetPicoRNA@cbs.dtu.dk or via WWW at http://www.cbs.dtu.dkfservices/NetPicoRNA.Keywords: cleavage site prediction; neural networks; picornavirus; proteinase; surface exposureMembers of the picornavirus family express their genomic RNA as a single polyprotein that is proteolytically processed to the mature polypeptides. At least three proteinases are required for the individual protein components to be released (reviewed in Krausslich Hellen et al., 1989;Lawson & Semler, 1990). The primary cleavage, which severs the capsid precursor PI from the nonstructural region P2-P3, is performed cotranslationally by the viral proteinase 2APm in enteroviruses and human rhinoviruses (HRVs; see Fig. I). Most of the remaining cleavages are catalyzed by the viral proteinase, 3CP". In cardio-, hepato-, and aphthoviruses, which also belong to the picornavirus family, the L-proteinase performs functions similar to those of 2APm, resulting in a somewhat different cleavage scheme (see Fig. I). Concomitantly with RNA encapsidation, VPO is cleaved to VP4 and VP2; it is believed that the RNA itself exerts a catalytic function in this event (Arnold et a!., 1987;Harber et al., 1991;Bishop &Anderson, 1993;Basavappa et al., 1994).In addition to processing of the viral polyprotein, the proteinases also cleave cellular targets. When infected with poliovirus, at least nine acidic and five basic cellular proteins were shown to be degraded in two-dimensional gel electrophoresis (Urzanqui & Carrasco, 1989). The degradation of cellular proteins seems to be part of the viral attack mechanism, leading to host cell shur-ofJ-a decrease in cellular transcription and translation that has no influence on viral replication. The best-studied event is the cleavage of the eukaryotic initiation factor 4G (eIF-4G). which is required for cap-dependent translation of cellular mRNA. This protein is degraded by 2APm in entero-and...

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Mapping of Functional Domains in Eukaryotic Protein Synthesis Initiation Factor 4G (eIF4G) with Picornaviral Proteases

Cited by 534 publications

References 65 publications

Conducting the initiation of protein synthesis: the role of eIF4G

Conducting the initiation of protein synthesis: the role of eIF4G

Cleavage of DAP5 by coxsackievirus B3 2A protease facilitates viral replication and enhances apoptosis by altering translation of IRES-containing genes

Cleavage site analysis in picornaviral polyproteins: Discovering cellular targets by neural networks

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