The potyviral virus genome-linked protein VPg forms a ternary complex with the eukaryotic initiation factors eIF4E and eIF4G and reduces eIF4E affinity for a mRNA cap analogue.
The virus protein linked to the genome (VPg) of plant potyviruses is a 25-kDa protein covalently attached to the genomic RNA 5' end. It was previously reported that VPg binds specifically to eIF4E, the mRNAcap-binding protein of the eukaryotic translation initiation complex. We performed a spectroscopic study of the interactions between lettuce eIF4E and VPg from lettuce mosaic virus (LMV). The cap analogue m7GDP and VPg bind to eIF4E at two distinct sites with similar affinity (K(d) = 0.3 microm). A deeper examination of the interaction pathway showed that the binding of one ligand induces a decrease in the affinity for the other by a factor of 15. GST pull-down experiments from plant extracts revealed that VPg can specifically trap eIF4G, the central component of the complex required for the initiation of protein translation. Our data suggest that eIF4G recruitment by VPg is indirectly mediated through VPg-eIF4E association. The strength of interaction between eIF4E and pep4G, the eIF4E-binding domain on eIF4G, was increased significantly by VPg. Taken together these quantitative data show that VPg is an efficient modulator of eIF4E biochemical functions.
Michon
Thierry
T
Interactions Plante-Virus, UMR GDPP INRA-Bordeaux 2, Institut de Biologie Végétale Moléculaire, Villenave d'Ornon, France. michon@bordeaux.inra.fr
Estevez
Yannick
Y
Walter
Jocelyne
J
German-Retana
Sylvie
S
Le Gall
Olivier
O
D001665:Binding Sites / Q000235:genetics; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D039502:Nuclear Cap-Binding Protein Complex; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D012314:RNA Cap Analogs / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D039502:Nuclear Cap-Binding Protein Complex; D010940:Plant Proteins; D012314:RNA Cap Analogs; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D017361:Viral Nonstructural Proteins; C102206:genome-linked viral protein, potato virus Y; D005982:Glutathione Transferase