Structural Comparison of Monomeric Variants of the Chemokine MIP-1 Having Differing Ability To Bind the Receptor CCR5

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• 作者：Seho Kim ; Shu-chuan Jao ; Jennifer S. Laurence ; and Patricia J. LiWang
• 刊名：Biochemistry
• 出版年：2001
• 出版时间：September 11, 2001
• 年：2001
• 卷：40
• 期：36
• 页码：10782 - 10791
• 全文大小：341K
• 年卷期：v.40,no.36(September 11, 2001)
• ISSN：1520-4995

文摘

MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">, a member of the chemokine family of proteins, tightly binds the receptor CCR5 aspart of its natural function in the immune response, and in doing so also blocks the ability of many strainsof HIV to enter the cell. The single most important MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> residue known to contribute to its interactionwith the receptor is Phe13, which when mutated reduces the ability of MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> to bind to CCR5 by morethan 1000-fold. To obtain a structural understanding of the dramatic effect of the absence of Phe13 inMIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">, we used multidimensional heteronuclear NMR to determine the three-dimensional structure ofthe MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> F13A variant. We had previously shown that, unlike the wild-type protein which has beenshown to be a tight dimer, the F13A mutant is monomeric even at high concentrations [Laurence, J. S.,Blanpain, C., Burgner, J. W., Parmentier, M., and LiWang, P. J. (2000) Biochemistry 39, 3401-3409],leading to significant changes in the NMR spectra of F13A and the wild-type protein. We have obtaineda total of 940 structural restraints for MIP-1mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> F13A, and have calculated a family of structures having abackbone rmsd from the average of 0.55 Å (residues 12-67). A structural comparison of the F13A mutantwith a fully active monomeric variant, P8A, shows that despite some differences in the ¹H-¹⁵N HSQCspectra the two are nearly identical in NOE distance restraints and in backbone conformation. A comparisonof F13A with the wild-type protein shows largely the same fold, although differences exist in the N-terminaland loop regions for which the loss of the dimer in F13A can mainly account. A dynamics comparisonconfirms greater flexibility in F13A than in the wild-type protein in regions of dimer contact in the wild-type protein. In an analysis to determine if the large functional effect resulting from the loss of Phe13 isdue to the local side chain change or due to more global structural changes, we conclude that local effectspredominate. This suggests that a strategy for designing tight binding anti-CCR5 therapeutics shouldinclude a Phe-like component.