vanderSpek Johanna C, Sutherland John A, Gill Brian M, Gorgun Gullu, Foss Francine M, Murphy John R
Evans Department of Clinical Research and the Department of Medicine, Boston Medical Center, Boston, Massachusetts, 02118, USA.
Cytokine. 2002 Mar 7;17(5):227-33. doi: 10.1006/cyto.2002.1004.
The residues located at the carboxyl terminus of helix D in interleukin-7 (IL-7) have previously been targeted as important for recruitment and binding to the gamma chain component of the IL-7 receptor (IL-7R). In this study, Trp 143 of helix D was mutated to His, Phe, Tyr and Pro and these mutants, along with a W143A mutant previously described, were studied to determine the effects on activation of DNA synthesis and binding affinity to IL-7R positive 2E8 cells. The W143F and W143Y mutants were similar to wild type IL-7 in their binding properties and retained 85% and 74% of their activating properties, respectively. In contrast, the W143H mutant possessed a lower binding affinity and a corresponding decrease in activation, the W143A mutant possessed an over 100-fold decreased binding affinity and some residual activation activity and the W143P mutant possessed a greatly decreased binding affinity and did not activate. These results strongly suggest an aromatic residue is required at position 143 for IL-7R binding and subsequent signal transduction.
白细胞介素-7（IL-7）中D螺旋羧基末端的残基先前已被确定为对招募和结合IL-7受体（IL-7R）的γ链成分很重要。在本研究中，将D螺旋的Trp 143突变为His、Phe、Tyr和Pro，并对这些突变体以及先前描述的W143A突变体进行研究，以确定其对DNA合成激活和与IL-7R阳性2E8细胞结合亲和力的影响。W143F和W143Y突变体在结合特性上与野生型IL-7相似，分别保留了85%和74%的激活特性。相比之下，W143H突变体具有较低的结合亲和力，激活作用相应降低；W143A突变体的结合亲和力降低了100倍以上，但仍有一些残余的激活活性；W143P突变体的结合亲和力大幅降低且无激活作用。这些结果强烈表明，143位需要一个芳香族残基来实现IL-7R结合及后续信号转导。
