Salinas F, Kodadek T
Department of Chemistry and Biochemistry, University of Texas at Austin 78712.
Biochem Biophys Res Commun. 1994 Dec 15;205(2):1004-9. doi: 10.1006/bbrc.1994.2766.
The phage T4 uvsX and gene 32 proteins are capable of mediating homologous strand exchange, a central reaction in general genetic recombination, in vitro using naked DNA substrates. However, strand exchange is blocked by a sequence specific DNA-protein complex. Since protein-complexed substrates must be employed in vivo, this suggests that another factor(s) is required for strand exchange with protein-complexed DNAs. We show here that a DNA helicase, the T4 dda protein, allows the phage recombination machinery to drive branch migration through a RNA polymerase-promoter complex. This is the first observation of in vitro strand exchange using protein-bound substrates. These results suggest that a DNA helicase is a necessary component of the "protein machine" that mediates recombination in vivo.
噬菌体T4的uvsX蛋白和基因32蛋白能够在体外使用裸露的DNA底物介导同源链交换，这是一般遗传重组中的核心反应。然而，链交换被一种序列特异性DNA-蛋白质复合物所阻断。由于在体内必须使用与蛋白质复合的底物，这表明与蛋白质复合的DNA进行链交换还需要其他因素。我们在此表明，一种DNA解旋酶，即T4 dda蛋白，能使噬菌体重组机制驱动分支迁移通过RNA聚合酶-启动子复合物。这是首次观察到使用与蛋白质结合的底物进行体外链交换。这些结果表明，DNA解旋酶是在体内介导重组的“蛋白质机器”的必要组成部分。
