Sauer R T, Ross M J, Ptashne M
J Biol Chem. 1982 Apr 25;257(8):4458-62.
The site of recA cleavage of the phage lambda and P22 repressors has been determined. Each repressor is cut once by the recA enzyme, lambda repressor between residues 111 and 112, and P22 repressor between residues 94 and 95. recA cleavage occurs at identical alanyl-glycyl sequences in both repressors, and in both repressors, the cleavage separates the repressor's NH2-terminal DNA-binding domain from its COOH-terminal oligomerization domain. A papain-generated proteolytic fragment of lambda repressor consisting of repressor residues 93-236 is also efficiently cleaved by recA protein. Moreover, the recA cleavage of radioactive lambda repressor can be inhibited by certain COOH-terminal proteolytic fragments of lambda repressor which do not contain the alanyl-glycyl cleavage sequence. These facts suggest that recA cleavage of lambda repressor requires an intact COOH-terminal domain but not an intact NH2-terminal domain.
噬菌体λ和P22阻遏物的recA切割位点已被确定。每种阻遏物都被recA酶切割一次，λ阻遏物在第111和112位残基之间被切割，P22阻遏物在第94和95位残基之间被切割。recA切割在两种阻遏物相同的丙氨酰-甘氨酰序列处发生，并且在两种阻遏物中，切割都将阻遏物的NH2末端DNA结合结构域与其COOH末端寡聚化结构域分开。由λ阻遏物的第93 - 236位残基组成的木瓜蛋白酶产生的蛋白水解片段也能被recA蛋白有效切割。此外，放射性λ阻遏物的recA切割可被λ阻遏物的某些不包含丙氨酰-甘氨酰切割序列的COOH末端蛋白水解片段抑制。这些事实表明，λ阻遏物的recA切割需要完整的COOH末端结构域，但不需要完整的NH2末端结构域。
