CC Chemokine MIP-1 Can Function As a Monomer and Depends on Phe13 for Receptor Binding

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• 作者：Jennifer S. Laurence ; Cedric Blanpain ; John W. Burgner ; Marc Parmentier ; and Patricia J. LiWang
• 刊名：Biochemistry
• 出版年：2000
• 出版时间：March 28, 2000
• 年：2000
• 卷：39
• 期：12
• 页码：3401 - 3409
• 全文大小：103K
• 年卷期：v.39,no.12(March 28, 2000)
• ISSN：1520-4995

文摘

The reported structures of many CC chemokines show a conserved dimer interface along theirN-terminal region, raising the possibility that the quaternary arrangement of these small immune proteinsmight influence their function. We have produced and analyzed several mutants of MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> having arange of dimer K_d values in order to determine the significance of dimerization in receptor binding andcellular activation. NMR and analytical ultracentrifugation were used to analyze the oligomeric state ofthe mutants. Functional relevance was determined by receptor binding affinity and the ability to invokeintracellular calcium release from CHO cells transfected with the MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> receptor CCR5. The monomericN-terminally truncated mutant MIP(9) was able to bind the CCR5 receptor with a K_i of 600 pM butdisplayed weak agonistic properties, while the monomeric mutant P8A still retained the ability to tightlybind (K_i = 480 pM) and to activate (EC₅₀ = 12 nM) the receptor. These data suggest that the MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">dimer is not required for CCR5 binding or activation. In addition, we identified Phe13, the residueimmediately following the conserved CC motif in MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">, as a key determinant for binding to CCR5.Replacement of Phe13 by Tyr, Leu, Lys, and Ala showed the aromatic side chain to be important for bothbinding to CCR5 and chemokine dimerization.