Finan P, Koga H, Zvelebil M J, Waterfield M D, Kellie S
Yamanouchi Research Institute, Littlemore Hospital, Oxford, UK.
J Mol Biol. 1996 Aug 16;261(2):173-80. doi: 10.1006/jmbi.1996.0450.
Src-homology 3 (SH3) domains are small protein modules that bind to proline-rich motifs and mediate the formation of signalling complexes. SH3 domains have been implicated in the assembly of the phagocyte NADPH oxidase complex, a multicomponent enzyme responsible for the production of antimicrobial oxidants. Two components of the NADPH oxidase, p67phox and p47phox, each contain two SH3 domains and we have previously shown that the SH3 domain near the carboxyl terminus of p67phox interacts with a proline-rich region of p47phox. In order to gain an insight into the specificity of this interaction, a structural model of the p67phox SH3 domain has been produced using the known structure of the c-abl SH3 domain as a template. The model suggests that the proline-rich ligand of p47phox can bind to the SH3 domain in either of two orientations. In each orientation, the key residues of the SH3 domain that contact the ligand have been identified and altered by site-directed mutagenesis. The ability of the mutated SH3 domains to associate with p47phox from cell lysates was tested and the results provide the first evidence for the binding of a full-length protein to an SH3 domain in a reversed orientation.
Src同源结构域3（SH3）是一种小的蛋白质模块，可与富含脯氨酸的基序结合并介导信号复合物的形成。SH3结构域与吞噬细胞NADPH氧化酶复合物的组装有关，该复合物是一种负责产生抗菌氧化剂的多组分酶。NADPH氧化酶的两个组分p67phox和p47phox各自含有两个SH3结构域，我们之前已经表明p67phox羧基末端附近的SH3结构域与p47phox的富含脯氨酸区域相互作用。为了深入了解这种相互作用的特异性，已使用c-abl SH3结构域的已知结构作为模板构建了p67phox SH3结构域的结构模型。该模型表明，p47phox富含脯氨酸的配体可以以两种方向之一与SH3结构域结合。在每个方向上，已通过定点诱变鉴定并改变了与配体接触的SH3结构域的关键残基。测试了突变的SH3结构域与细胞裂解物中p47phox结合的能力，结果为全长蛋白质以反向方向与SH3结构域结合提供了首个证据。
