Glycosylation, disulfide bond formation, and the presence of a WSXWS-like motif in the orf virus GIF protein are critical for maintaining the integrity of Binding to ovine granulocyte-macrophage colony-stimulating factor and interleukin-2.
Orf virus (ORFV), the type species of the family Parapoxviridae, encodes a protein (GIF) that binds and inhibits the ovine cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2). There is no obvious sequence homology between the ORFV protein and any known mammalian GM-CSF- or IL-2-binding proteins. We demonstrate here that many of the biochemical properties of mammalian GM-CSF receptors that are required for efficient binding of GM-CSF are also critical to the GIF protein for binding to ovine GM-CSF (ovGM-CSF). Site-directed mutagenesis of the GIF protein demonstrated, first, the importance of disulfide bonds, and second, that a sequence motif (WDPWV), related to the WSXWS motif of the type 1 cytokine receptor superfamily, was necessary for biological activity. Finally, glycosylation of the GIF protein was also critical for binding to GM-CSF.
McInnes
C J
CJ
Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, UK. mcinc@mri.sari.ac.uk
Deane
D
D
Haig
D
D
Percival
A
A
Thomson
J
J
Wood
A R
AR
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D004220:Disulfides; D006031:Glycosylation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D007376:Interleukin-2 / Q000378:metabolism*; D008969:Molecular Sequence Data; D009923:Orf virus / Q000502:physiology*; D011485:Protein Binding; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
D004220:Disulfides; C403419:GIF protein, orf virus; D007376:Interleukin-2; D014764:Viral Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor