tailieunhanh - Báo cáo khoa học: Binding of the viral immunogenic octapeptide VSV8 to native glucose-regulated protein Grp94 (gp96) and its inhibition by the physiological ligands ATP and Ca2+ Ming Ying and Torgeir Flatmark

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. | ềFEBS Journal Binding of the viral immunogenic octapeptide VSV8 to native glucose-regulated protein Grp94 gp96 and its inhibition by the physiological ligands ATP and Ca2 Ming Ying and Torgeir Flatmark Section of Biochemistry and Molecular Biology Department of Biomedicine University of Bergen Norway Keywords ATP cations Grp94 SPR VSV8 Correspondence T. Flatmark Section of Biochemistry and Molecular Biology Department of Biomedicine University of Bergen Jonas Lies vei 91 N-5009 Bergen Norway Fax 47 55 586360 Tel 47 55 586428 E-mail Received 30 September 2005 revised 1 December 2005 accepted 2 December 2005 doi 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 C with the viral immunogenic octapeptide RGYVYQGL VSV8 derived from vesicular stomatitis virus nucleoprotein 52-59 . The peptide binds reversibly with low affinity A 640 pM 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. Grp94 gp96 a major chaperone of the ER lumen and a paralogue of the cytoplasmic chaperone Hsp90 plays an essential role in the structural maturation and or secretion of