TY - JOUR
T1 - Mutational Analysis of the Ligand-Binding Domain of M-T2 Protein, the Tumor Necrosis Factor Receptor Homologue of Myxoma Virus
AU - Schreiber, Martha
AU - McFadden, Grant
N1 - Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 1996/11/15
Y1 - 1996/11/15
N2 - The myxoma virus-encoded M-T2 protein shares extensive sequence homology with the ligand-binding domains of the TNF receptors (TNFRs) and has been shown to bind and inhibit rabbit TNF-α with affinities similar to those of TNF-α with cellular receptors. Here we show that M-T2 protein is secreted from infected cells as an N-linked glycoprotein, with both complex and hybrid or high mannose oligosaccharide chains. Since amino acid homology between M-T2 and cellular TNF receptors is limited to the four N-terminal cysteine-rich domains (CRDs), various M-T2 C-terminal truncations were created in recombinant vaccinia virus vectors. C-terminal deletions that include truncations up to the middle of the fourth CRD effectively bound and inhibited rabbit TNF-α. In contrast, removal of any one of the first three CRDs resulted in a mutant M-T2 protein incapable of binding or inhibiting rabbit TNF-α. The C-terminal portion of M-T2, which is not homologous to the cellular TNFRs, appears to be important for efficient secretion of M-T2 from infected cells, since all the C-terminal truncations, including a truncation removing only the last 24 amino acids, were effectively retained as intracellular proteins that were still capable of binding and inhibiting rabbit TNF-α. We conclude that the first three CRDs of M-T2 fulfill the same ligand-binding function as the cellular TNFRs, and the nonhomologous C-terminal region participates in protein trafficking of M-T2 in virus-infected cells.
AB - The myxoma virus-encoded M-T2 protein shares extensive sequence homology with the ligand-binding domains of the TNF receptors (TNFRs) and has been shown to bind and inhibit rabbit TNF-α with affinities similar to those of TNF-α with cellular receptors. Here we show that M-T2 protein is secreted from infected cells as an N-linked glycoprotein, with both complex and hybrid or high mannose oligosaccharide chains. Since amino acid homology between M-T2 and cellular TNF receptors is limited to the four N-terminal cysteine-rich domains (CRDs), various M-T2 C-terminal truncations were created in recombinant vaccinia virus vectors. C-terminal deletions that include truncations up to the middle of the fourth CRD effectively bound and inhibited rabbit TNF-α. In contrast, removal of any one of the first three CRDs resulted in a mutant M-T2 protein incapable of binding or inhibiting rabbit TNF-α. The C-terminal portion of M-T2, which is not homologous to the cellular TNFRs, appears to be important for efficient secretion of M-T2 from infected cells, since all the C-terminal truncations, including a truncation removing only the last 24 amino acids, were effectively retained as intracellular proteins that were still capable of binding and inhibiting rabbit TNF-α. We conclude that the first three CRDs of M-T2 fulfill the same ligand-binding function as the cellular TNFRs, and the nonhomologous C-terminal region participates in protein trafficking of M-T2 in virus-infected cells.
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M3 - Article
C2 - 8906826
AN - SCOPUS:0030588633
SN - 0022-1767
VL - 157
SP - 4486
EP - 4495
JO - Journal of Immunology
JF - Journal of Immunology
IS - 10
ER -