Cleavage of eIF4G by HIV-1 protease: effects on translation.
We have recently reported that HIV-1 protease (PR) cleaves the initiation factor of translation eIF4GI [Ventoso et al., Proc. Natl. Acad. Sci. USA 98 (2001) 12966-12971]. Here, we analyze the proteolytic activity of HIV-1 PR on eIF4GI and eIF4GII and its implications for the translation of mRNAs. HIV-1 PR efficiently cleaves eIF4GI, but not eIF4GII, in cell-free systems as well as in transfected mammalian cells. This specific proteolytic activity of the retroviral protease on eIF4GI was more selective than that observed with poliovirus 2A(pro). Despite the presence of an intact endogenous eIF4GII, cleavage of eIF4GI by HIV-1 PR was sufficient to impair drastically the translation of capped and uncapped mRNAs. In contrast, poliovirus IRES-driven translation was unaffected or even enhanced by HIV-1 PR after cleavage of eIF4GI. Further support for these in vitro results has been provided by the expression of HIV-1 PR in COS cells from a Gag-PR precursor. Our present findings suggest that eIF4GI intactness is necessary to maintain cap-dependent translation, not only in cell-free systems but also in mammalian cells.
Perales
Celia
C
Centro de Biologi;a Molecular 'Severo Ochoa', Facultad de Ciencias, Universidad Autónoma-CSIC, Cantoblanco 28049, Madrid, Spain.
Carrasco
Luis
L
Ventoso
Iván
I
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002474:Cell-Free System; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D039603:Eukaryotic Initiation Factor-4G / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016333:HIV Protease / Q000378:metabolism*; D015497:HIV-1 / Q000201:enzymology / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D017955:Poliovirus / Q000201:enzymology / Q000235:genetics; D014176:Protein Biosynthesis; D012315:RNA Caps / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins
D039603:Eukaryotic Initiation Factor-4G; D012315:RNA Caps; D012333:RNA, Messenger; D012367:RNA, Viral; D011994:Recombinant Proteins; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C057400:picornain 2A, Picornavirus; D016333:HIV Protease