Poliovirus 2A proteinase cleaves directly the eIF-4G subunit of eIF-4F complex.
The initiation of translation on eukaryotic mRNA is governed by the concerted action of polypeptides of the eIF-4F complex. One of these polypeptides, eIF-4G, is proteolytically inactivated upon infection with several members of the Picornaviridae family. This cleavage occurs by the action of virus-encoded proteinases: 2Apro (entero- and rhinovirus) or Lpro (aphthovirus). An indirect mode of eIF-4G cleavage through the activation of a second cellular proteinase has been proposed in the case of poliovirus. Although cleavage of eIF4G by rhino- and coxsackievirus 2Apro has been achieved directly in vitro, a similar activity has not been documented to date for poliovirus 2Apro. We report here that a recombinant form of poliovirus 2Apro fused to maltose binding protein (MBP) directly cleaves human eIF-4G from a highly purified eIF-4F complex. Efficient cleavage of eIF-4G requires magnesium ions. The presence of other initiation factors such as eIF-3, eIF-4A or eIF-4B mimics in part the stimulatory effect of magnesium ions and probably stabilizes the cleavage products of eIF-4G generated by 2Apro. These results suggest that efficient cleavage of eIF4G by MBP-2Apro requires a proper conformation of this factor. Finally, MBP-2Apro protein cleaves an eIF-4G-derived synthetic peptide at the same site as rhino- and coxsackievirus 2Apro (R485-G486).
Centro de Biologia Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, Spain. iventoso@trasto.cbm.uam.es
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I
Ventoso
S E
SE
MacMillan
J W
JW
Hershey
L
L
Carrasco
D002352:Carrier Proteins / Q000235:genetics; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D039562:Eukaryotic Initiation Factor-4F; D039603:Eukaryotic Initiation Factor-4G; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D046911:Macromolecular Substances; D008320:Maltose / Q000378:metabolism; D058619:Maltose-Binding Proteins; D010448:Peptide Initiation Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism; D017955:Poliovirus / Q000201:enzymology*; D014764:Viral Proteins
D002352:Carrier Proteins; D039562:Eukaryotic Initiation Factor-4F; D039603:Eukaryotic Initiation Factor-4G; D046911:Macromolecular Substances; D058619:Maltose-Binding Proteins; D010448:Peptide Initiation Factors; D010455:Peptides; D014764:Viral Proteins; D008320:Maltose; D003546:Cysteine Endopeptidases; C057400:picornain 2A, Picornavirus