Bouché J P, Zechel K, Kornberg A
J Biol Chem. 1975 Aug 10;250(15):5995-6001.
The protein responsible for the initiation of conversion of single-stranded phage G4 DNA to the duplex replicative form has been purified approximately 3000-fold and identified with Escherichia coli dnaG gene product. The protein is a rifampicin-resistant RNA polymerase of approximately 64,000 daltons. It catalyzes the incorporation of the four ribonucleoside triphosphates into an oligoribonucleotide, using as template the single-stranded DNA coated with the DNA unwinding protein of E. coli. An RNA transcript of a unique region of the chromosome can serve as a primer by covalent extension by DNA polymerase III holoenzyme to form a nearly full-length linear complementary strand. A similar role for the dnaG protein in the initiation of nascent (Okazaki) fragments in replication of the host chromosome is discussed.
负责将单链噬菌体G4 DNA转化为双链复制形式起始过程的蛋白质已被纯化约3000倍，并被鉴定为大肠杆菌dnaG基因产物。该蛋白质是一种分子量约为64,000道尔顿的耐利福平RNA聚合酶。它催化四种核糖核苷三磷酸掺入寡核糖核苷酸中，以被大肠杆菌DNA解旋蛋白包被的单链DNA作为模板。染色体独特区域的RNA转录本可通过DNA聚合酶III全酶的共价延伸作为引物，以形成几乎全长的线性互补链。文中还讨论了dnaG蛋白在宿主染色体复制中新生（冈崎）片段起始过程中的类似作用。
