Localization of the major NF-kappaB-activating site and the sole TRAF3 binding site of LMP-1 defines two distinct signaling motifs.
The TRAF3 molecule interacts with the cytoplasmic carboxyl terminus (COOH terminus) of the Epstein-Barr virus-encoded oncogene LMP-1. NF-kappaB activation is a downstream signaling event of tumor necrosis factor receptor-associated factor (TRAF) molecules in other signaling systems (CD40 for example) and is an event caused by LMP-1 expression. One region capable of TRAF3 interaction in LMP-1 is the membrane-proximal 45 amino acids (188-242) of the COOH terminus. We show that this region contains the only site for binding of TRAF3 in the 200-amino acid COOH terminus of LMP-1. The site also binds TRAF2 and TRAF5, but not TRAF6. TRAF3 binds to critical residues localized between amino acids 196 and 212 (HHDDSLPHPQQATDDSG), including the PXQX(T/S) motif, that share limited identity to the CD40 receptor TRAF binding site (TAAPVQETL). Mutation of critical residues in the TRAF3 binding site of LMP-1 that prevents binding of TRAF2, TRAF3, and TRAF5 does not affect NF-kappaB-activating potential. Deletion mapping localized the major NF-kappaB activating region of LMP-1 to critical residues in the distal 4 amino acids of the COOH terminus (383-386). Therefore, TRAF3 binding and NF-kappaB activation occur through two separate motifs at opposite ends of the LMP-1 COOH-terminal sequence.
Brodeur
S R
SR
Department of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Cheng
G
G
Baltimore
D
D
Thorley-Lawson
D A
DA
D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D002213:Capsid; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D048008:TNF Receptor-Associated Factor 3; D014407:Tumor Cells, Cultured; D014763:Viral Matrix Proteins / Q000378:metabolism*; D016335:Zinc Fingers
D000956:Antigens, Viral; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D016328:NF-kappa B; D009856:Oncogene Proteins, Viral; D011506:Proteins; D048008:TNF Receptor-Associated Factor 3; D014763:Viral Matrix Proteins