Solution structure and dynamics of the CX3C chemokine domain of fractalkine and its interaction with an N-terminal fragment of CX3CR1
Solution structure and dynamics of the CX3C chemokine domain of fractalkine and its interaction with an N-terminal fragment of CX3CR1
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DOI：
10.1021/bi9820614
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发表时间：
1999-02-02
期刊：
影响因子：
2.9
通讯作者：
Handel, TM
中科院分区：
文献类型：
--
作者：
Mizoue, LS;Bazan, JF;Handel, TM
Fractalkine是一种新的CX 3C趋化因子，由于其膜相关结构和其在细胞粘附中的直接作用而不寻常。我们已经解决了趋化因子结构域的fractalkine（残基1-76）的解决方案结构的异频NMR方法。系综中的20个最低能量结构具有0.43埃的平均骨架rmsd，不包括末端。与形成同源二聚体的许多其他趋化因子相反，fractalkine的趋化因子模块是单体的。CC和CXC趋化因子的结构比较揭示了可能与受体结合相关的有趣差异。这些包括由CX 3C基序形成的凸起、N-末端和30 ′环（残基30-38）的相对取向以及N-环（残基9-19）的构象。N-15骨架松弛实验表明，这些相同的蛋白质区域是动态的。我们还用来自受体CX（3）CR 1 N端的肽滴定了N-15标记的蛋白质，并证实受体的这一区域与fractalkine趋化因子结构域接触。有趣的是，结合位点大致映射到最大的灵活性和结构变异性的区域。总之，这些数据提供了fractalkine如何与其受体相互作用的第一个一瞥，并应有助于指导诱变研究，以进一步阐明通过CX（3）CR 1结合和信号传导的分子细节。
Fractalkine, a novel CX3C chemokine, is unusual because of both its membrane-associated structure and its direct role in cell adhesion. We have solved the solution structure of the chemokine domain of fractalkine (residues 1-76) by heteronuclear NMR methods. The 20 lowest energy structures in the ensemble have an average backbone rmsd of 0.43 Angstrom, excluding the termini. In contrast to many other chemokines which form homodimers, fractalkine's chemokine module is monomeric. Comparison of the structure to CC and CXC chemokines reveals interesting differences which are Likely to be relevant to receptor binding. These include a bulge formed by the CX3C motif, the relative orientation of the N-terminus and 30's loop (residues 30-38), and the conformation of the N-loop (residues 9-19). N-15 backbone relaxation experiments indicate that these same regions of the protein are dynamic. We also titrated N-15-labeled protein with a peptide from the N-terminus of the receptor CX(3)CR1 and confirmed that this region of the receptor contacts the fractalkine chemokine domain. Interestingly, the binding site maps roughly to the regions of greatest flexibility and structural variability. Together, these data provide a first glimpse of how fractalkine interacts with its receptor and should help guide mutagenesis studies to further elucidate the molecular details of binding and signaling through CX(3)CR1.