Cloning and characterization of hIF2, a human homologue of bacterial translation initiation factor 2, and its interaction with HIV-1 matrix.
The cDNA for a human homologue (hIF2) of bacterial (bIF2) and yeast (yIF2) translation initiation factor two (IF2) has been identified during a screen for proteins which interact with HIV-1 matrix. The hIF2 cDNA encodes a 1220-amino-acid protein with a predicted relative molecular mass of 139 kDa, though endogeneous hIF2 migrates anomalously on SDS/PAGE at 180 kDa. hIF2 has an extended N-terminus compared with its homologues, although its central GTP-binding domain and C-terminus are highly conserved, with 58% sequence identity with yIF2. We have confirmed that hIF2 is required for general translation in human cells by generation of a point mutation in the P-loop of the GTP-binding domain. This mutant protein behaves in a transdominant manner in transient transfections and leads to a significant decrease in the translation of a reporter gene. hIF2 interacts directly with HIV-1 matrix and Gag in vitro, and the protein complex can be immunoprecipitated from human cells. This interaction appears to block hIF2 function, since purified matrix protein inhibits translation in a reticulocyte lysate. hIF2 does not correspond to any of the previously characterized translation initiation factors identified in mammals, but its essential role in translation appears to have been conserved from bacteria to humans.
Wilson
S A
SA
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K. stuart.wilson@umist.ac.uk
Sieiro-Vazquez
C
C
Edwards
N J
NJ
Iourin
O
O
Byles
E D
ED
Kotsopoulou
E
E
Adamson
C S
CS
Kingsman
S M
SM
Kingsman
A J
AJ
Martin-Rendon
E
E
D000595:Amino Acid Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D015852:Eukaryotic Initiation Factor-2 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D005799:Genes, Dominant; D015488:HIV Antigens / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D039881:Prokaryotic Initiation Factor-2; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014764:Viral Proteins; D015003:Yeasts / Q000235:genetics; D054301:gag Gene Products, Human Immunodeficiency Virus
D015852:Eukaryotic Initiation Factor-2; D015683:Gene Products, gag; D015488:HIV Antigens; D039881:Prokaryotic Initiation Factor-2; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus; C054858:p17 protein, Human Immunodeficiency Virus Type 1