構造生物 Vol.3 No.1
1997年2月発行

The C-terminal SH3 Domain of p67phox Binds its Natural Ligand in a Reversed Orientation


Hironobu KOGA

Yamanouchi Pharmaceutical Co., Ltd.

Src-homology 3 (SH3) domains are small protein modules which bind to proline rich motifs and mediate the formation of signaling 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 carboxy-terminus of p67phox interacts with a proline-rich region of p47phox. In order to gain an insight into the specificy of this interaction a structural model of the p67phox SH3 domain has been made using the X-ray structure of the 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 the two known orientations. In each orientation, the key residues of the SH3 domain which 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 measured and the results provide experimental evidence that the physiological ligand for the c-terminal SH3 domain of p67phox binds in the reversed orientation. The results of these studies provide the first evidence for the binding of a full-length protein to an SH3 domain in a reversed orientation.


ご意見、ご要望などは下記のアドレスにメールを下さい。
sasaki@tara.met.nagoya-u.ac.jp