Andrake M, Guild N, Hsu T, Gold L, Tuerk C, Karam J
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston 29425.
Proc Natl Acad Sci U S A. 1988 Nov;85(21):7942-6. doi: 10.1073/pnas.85.21.7942.
In bacteriophage T4 the protein product of gene 43 (gp43) is a multifunctional DNA polymerase that is essential for replication of the phage genome. The protein harbors DNA-binding, deoxyribonucleotide-binding, DNA-synthesizing (polymerase) and 3'-exonucleolytic (editing) activities as well as a capacity to interact with several other T4-induced replication enzymes. In addition, the T4 gp43 is a repressor of its own synthesis in vivo. We show here that this protein is an autogenous repressor of translation, and we have localized its RNA-binding sequence (translational operator) to the translation initiation domain of gene 43 mRNA. This mechanism for regulation of T4 DNA polymerase expression underscores the ubiquity of translational repression in the control of T4 DNA replication. Many T4 DNA polymerase accessory proteins and nucleotide biosynthesis enzymes are regulated by the phage-induced translational repressor regA, while the T4 single-stranded DNA-binding protein (T4 gp32) is, like gp43, autogenously regulated at the translational level.
在噬菌体T4中，基因43的蛋白质产物（gp43）是一种多功能DNA聚合酶，对噬菌体基因组的复制至关重要。该蛋白质具有DNA结合、脱氧核糖核苷酸结合、DNA合成（聚合酶）和3'-核酸外切（编辑）活性，以及与其他几种T4诱导的复制酶相互作用的能力。此外，T4 gp43在体内是其自身合成的阻遏物。我们在此表明，该蛋白质是翻译的自体阻遏物，并且我们已将其RNA结合序列（翻译操纵子）定位到基因43 mRNA的翻译起始结构域。这种调节T4 DNA聚合酶表达的机制强调了翻译阻遏在T4 DNA复制控制中的普遍性。许多T4 DNA聚合酶辅助蛋白和核苷酸生物合成酶受噬菌体诱导的翻译阻遏物regA调节，而T4单链DNA结合蛋白（T4 gp32）与gp43一样，在翻译水平上受到自体调节。
