Binding of the viral immunogenic octapeptide VSV8 to native glucose-regulated protein Grp94 (gp96) and its inhibition by the physiological ligands ATP and Ca2+.
The molecular chaperone Grp94 (gp96) of the endoplasmic reticulum (ER) lumen plays an essential role in the structural maturation and/or secretion of proteins destined for transport to the cell surface. Its proposed role in binding and transferring peptides for immune recognition is, however, controversial. Using SPR spectroscopy, we studied the interaction of native glycosylated Grp94 at neutral pH and 25 and 37 degrees C with the viral immunogenic octapeptide RGYVYQGL (VSV8), derived from vesicular stomatitis virus nucleoprotein (52-59). The peptide binds reversibly with low affinity ([A]0.5 approximately 640 microM) and a hyperbolic binding isotherm, and the binding is partially inhibited by ATP and Ca2+ at concentrations that are present in the ER lumen, and the effects are explained by conformational changes in the native chaperone induced by these ligands. Our data present experimental support for the recent proposal that, under native conditions, VSV8 binds to Grp94 by an adsorptive, rather than a bioselective, mechanism, and thus further challenge the proposed in vivo peptide acceptor-donor function of the chaperone in the context of antigen-presenting cell activation.
Ying
Ming
M
Section of Biochemistry and Molecular Biology, Department of Biomedicine, University of Bergen, Norway.
Flatmark
Torgeir
T
D000255:Adenosine Triphosphate / Q000737:chemistry*; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000737:chemistry; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D009698:Nucleoproteins / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance / Q000379:methods; D014721:Vesicular stomatitis Indiana virus / Q000737:chemistry
D018840:HSP70 Heat-Shock Proteins; D008024:Ligands; D008565:Membrane Proteins; D009698:Nucleoproteins; D010446:Peptide Fragments; C018551:glucose-regulated proteins; C508900:vesicular stomatitis virus nucleoprotein (52-59); D019830:Adenosine-5'-(N-ethylcarboxamide); D000255:Adenosine Triphosphate; D002118:Calcium