title: Cleavage of poly(A)-binding protein by poliovirus 3C protease inhibits host cell translation: a novel mechanism for host translation shutoff.
abstract: Cleavage of eukaryotic translation initiation factor 4GI (eIF4GI) by viral 2A protease (2Apro) has been proposed to cause severe translation inhibition in poliovirus-infected cells. However, infections containing 1 mM guanidine-HCl result in eIF4GI cleavage but only partial translation shutoff, indicating eIF4GI cleavage is insufficient for drastic translation inhibition. Viral 3C protease (3Cpro) cleaves poly(A)-binding protein (PABP) and removes the C-terminal domain (CTD) that interacts with several translation factors. In HeLa cell translation extracts that exhibit cap-poly(A) synergy, partial cleavage of PABP by 3Cpro inhibited translation of endogenous mRNAs and reporter RNA as effectively as complete cleavage of eIF4GI and eIF4GII by 2Apro. 3Cpro-mediated translation inhibition was poly(A) dependent, and addition of PABP to extracts restored translation. Expression of 3Cpro in HeLa cells resulted in partial PABP cleavage and similar inhibition of translation. PABP cleavage did not affect eIF4GI-PABP interactions, and the results of kinetics experiments suggest that 3Cpro might inhibit late steps in translation or ribosome recycling. The data illustrate the importance of the CTD of PABP in poly(A)-dependent translation in mammalian cells. We propose that enteroviruses use a dual strategy for host translation shutoff, requiring cleavage of PABP by 3Cpro and of eIF4G by 2Apro.
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: N Muge
authors.initials: NM
authors.lastname: Kuyumcu-Martinez
authors.forename: Marc E
authors.initials: ME
authors.lastname: Van Eden
authors.forename: Patrick
authors.initials: P
authors.lastname: Younan
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lloyd
mesh_terms: D000086042:3C Viral Proteases; D002384:Catalysis; D002457:Cell Extracts; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000378:metabolism; D017955:Poliovirus / Q000201:enzymology*; D039102:Poly(A)-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D002457:Cell Extracts; C113920:EIF4G1 protein, human; C491300:EIF4G2 protein, human; D039603:Eukaryotic Initiation Factor-4G; D010446:Peptide Fragments; D010448:Peptide Initiation Factors; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases