Lee Seung-Joo, Richardson Charles C
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 2002 Oct 1;99(20):12703-8. doi: 10.1073/pnas.202471499. Epub 2002 Sep 12.
The interaction of primase monomers within the hexameric gene 4 helicase-primase of bacteriophage T7 has been examined by using two genetically distinct gene 4 proteins. The T7 56-kDa gene 4 protein differs from the full-length 63-kDa protein in that it lacks the N-terminal zinc motif essential for the recognition of primase recognition sites. A second gene 4 protein, gp4-K122A, is unable to catalyze the synthesis of phosphodiester bonds as the result of an amino acid change in the catalytic site. Although each protein alone is inactive, the two together catalyze the synthesis of RNA primers. Reconstitution of activity depends on hexamer formation. We propose that the zinc motif of one subunit in the hexamer interacts with the catalytic sites of adjacent subunits.
通过使用两种基因不同的基因4蛋白，对噬菌体T7的六聚体基因4解旋酶 - 引发酶中引发酶单体之间的相互作用进行了研究。T7 56 kDa的基因4蛋白与全长63 kDa的蛋白不同，它缺少识别引发酶识别位点所必需的N端锌基序。第二种基因4蛋白gp4-K122A由于催化位点的氨基酸变化而无法催化磷酸二酯键的合成。尽管每种蛋白单独时无活性，但两者共同催化RNA引物的合成。活性的重建取决于六聚体的形成。我们提出，六聚体中一个亚基的锌基序与相邻亚基的催化位点相互作用。
