Localization of the Major NF-κB-activating Site and the Sole TRAF3 Binding Site of LMP-1 Defines Two Distinct Signaling Motifs

Epstein–Barr virus latent membrane protein-1 (LMP1) signalling is distinct from CD40 and involves physical cooperation of its two C-terminus functional regions

“…Thus, a TRAF binding PxQxT motif is present in CD40 at aa 250 ± 254 and also in the CTAR1 region of LMP1 at aa 204 ± 208. Interestingly, while LMP1 CTAR1 was reported to bind TRAF1 as well as TRAF2, TRAF3 and TRAF5 through its PxQxT motif (Brodeur et al, 1997;Devergne et al, 1996;Mosialos et al, 1995;Sandberg et al, 1997), CD40 seems to associate only with TRAF2 and TRAF3 through this motif (Ishida et al, 1996;Rothe et al, 1995). It has been noted that di erences in the sequences adjacent to the PxQxT motif may in¯uence TRAF binding and signalling from CD40 and LMP1 (Eliopoulos et al, 1997;Franken et al, 1996).…”

Modulation of life and death by the TNF receptor superfamily

“…(The C-terminus of the protein is responsible for induction of the transformed state). As with CD40, altered expression of TRAF-3 mutants do not e ect NF-kB activation by LMP1 (Miller et al, 1997), and in fact, LMP1-induced NF-kB activation and TRAFmediated signaling are presumed to travel via independent pathways (Miller et al, 1997) through di erent LMP1 motifs (Brodeur et al, 1997). Because it is presumed that LMP1 sequesters TRAF proteins at the plasma membrane, its expression may mimic the e ects induced by members of the TNF superfamily such as CD40 (which, in conjunction with IL-4 treatment of primary B cells, induces the characteristics of EBV transformed cells) and LTb (Mosialos et al, 1995).…”

Epstein-Barr virus transformation: involvement of latent membrane protein 1-mediated activation of NF-κB

“…An LMP1 mutant in which P204 and Q206 are changed to alanines does not co-immunoprecipitate any TRAF from BJAB Burkitt's lymphoma or cervical carcinoma cells (Devergne et al, 1998). Likewise, an LMP1 CTD mutant in which T208 and D209 are converted to alanines fails to precipitate TRAF3 in binding assays (Brodeur et al, 1997). Although there are other sequences in the LMP1 CTD with identity to the core TRAF binding motif, they do not function as TRAF interaction sites (Brodeur et al, 1997;Devergne et al, 1998;Franken et al, 1996).…”

“…Likewise, an LMP1 CTD mutant in which T208 and D209 are converted to alanines fails to precipitate TRAF3 in binding assays (Brodeur et al, 1997). Although there are other sequences in the LMP1 CTD with identity to the core TRAF binding motif, they do not function as TRAF interaction sites (Brodeur et al, 1997;Devergne et al, 1998;Franken et al, 1996). LMP1 TES1/CTAR1 activates NF-kB about 25% as well as LMP1 when transiently expressed in 293 cells.…”

“…Recombinant viral genetic and biochemical analyses show that these two sites in the CTD of LMP1 are critical for growth transformation and activation of NF-kB (Huen et al, 1995;Kaye et al, 1995;Mitchell and Sugden, 1995). The ®rst region spans residues 187 ± 231 and constitutively interacts with the tumor necrosis factor (TNF) receptor associated factors TRAF1, TRAF2, TRAF3 and TRAF5 (Brodeur et al, 1997;Devergne et al, 1996Devergne et al, , 1998Mosialos et al, 1995). The second region of the CTD encompasses residues 352 ± 386 and this region continuously interacts with TNF receptor-associated death domain-containing protein (TRADD) and TNF receptor-interacting protein (RIP) (Eliopoulos et al, 1999a;Izumi et al, 1999; (Figure 1).…”