Glycosaminoglycan Disaccharide Alters the Dimer Dissociation Constant of the Chemokine MIP-1

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• 作者：Melissa A. McCornack ; Danielle M. Boren ; and Patricia J. LiWang
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：August 10, 2004
• 年：2004
• 卷：43
• 期：31
• 页码：10090 - 10101
• 全文大小：250K
• 年卷期：v.43,no.31(August 10, 2004)
• ISSN：1520-4995

文摘

Chemokines are immune system proteins that recruit and activate leukocytes to sites of infection.This recruitment is believed to involve the establishment of a chemokine concentration gradient by thebinding of chemokines to glycosaminoglycans (GAGs). In previous studies, we elucidated the GAG bindingsite of the chemokine MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> and implicated the involvement of the chemokine dimer in GAG bindingthrough residues across the dimer interface. In the present studies, nuclear magnetic resonance spectroscopywas used to investigate the effect of GAG binding on MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> dimerization. Using several dimerization-impaired variants of MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> (F13Y, F13L, L34W, and L34K), these studies indicate that the addition ofdisaccharide to the mutants increases their dimerization affinities. For MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> F13Y, the presence of thedisaccharide increases the chemokine dimerization affinity about 9-fold as evidenced by a decrease in thedimer dissociation constant from 610 to 66 mages/entities/mgr.gif">M. Even more dramatically, the dimerization affinity ofMIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> L34W also increases upon addition of disaccharide, with the dimer dissociation constant decreasingfrom 97 to 6.5 mages/entities/mgr.gif">M. After this effect for the mutants of MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> was shown, similar experiments wereconducted with the CC chemokine RANTES, and it was demonstrated that the presence of disaccharideincreases its dimerization affinity by almost 7-fold. These findings provide further evidence of theimportance of the dimer in chemokine function and provide the first quantitative investigation of the roleof GAGs in the manipulation of the MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> quaternary structure.