In vitro cleavage of eIF4GI but not eIF4GII by HIV-1 protease and its effects on translation in the rabbit reticulocyte lysate system.
In eukaryotic cells, protein synthesis is regulated by a set of initiation factors (eIF) that are required for recruiting the 40 S ribosomal subunit onto the mRNA molecule. Among these proteins, eIF4GI, which is targeted by picornaviral proteases, makes a bridge between the mRNA cap structure (via eIF4E) and the 40 S ribosome (via eIF3). Recently, internal ribosome entry segment (IRES) elements have been characterized in the genomic RNA of both simian immunodeficiency virus (SIV) and human immunodeficiency virus type 1 (HIV-1), suggesting that viral expression of these two viruses can be regulated at the translational level. Thus, by analogy with members of the picornavirus family, we have investigated the action of the HIV-1 protease on initiation factors eIF4GI and eIF4GII using cell extracts and the rabbit reticulocyte lysate system. Our results show that eIF4GI, but not eIF4GII, is substrate for HIV-1 protease and this effect can be prevented by a HIV-1 protease inhibitor, palinavir. However, in contrast to picornaviral proteases, the cleavage of eIF4GI by HIV-1 protease occurs at multiple sites and impairs translation of both cap-dependent and IRES-containing RNAs, except for the HCV IRES, which does not require eIF4GI or eIF4GII for activity.
Ohlmann
Théophile
T
LaboRetro, Inserm U412, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon cedex 07, France. tohlmann@ens-lyon.fr
Prévôt
Déborah
D
Décimo
Didier
D
Roux
Florence
F
Garin
Jérôme
J
Morley
Simon J
SJ
Darlix
Jean-Luc
JL
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D039603:Eukaryotic Initiation Factor-4G; D016333:HIV Protease / Q000235:genetics / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000494:pharmacology; D015497:HIV-1 / Q000201:enzymology* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007938:Leukemia; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology*; D011804:Quinolines / Q000494:pharmacology; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D012156:Reticulocytes; D012270:Ribosomes / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
C113920:EIF4G1 protein, human; C491300:EIF4G2 protein, human; D039603:Eukaryotic Initiation Factor-4G; D017320:HIV Protease Inhibitors; D010446:Peptide Fragments; D010448:Peptide Initiation Factors; D011804:Quinolines; D011994:Recombinant Proteins; C107199:palinavir; D016333:HIV Protease; D014633:Valine