dnaX基因编码DNA聚合酶III全酶的τ亚基，γ亚基的前体，即dnaZ基因产物。

The dnaX gene encodes the DNA polymerase III holoenzyme tau subunit, precursor of the gamma subunit, the dnaZ gene product.

作者信息

Kodaira M, Biswas S B, Kornberg A

出版信息

Mol Gen Genet. 1983;192(1-2):80-6. doi: 10.1007/BF00327650.

DOI:10.1007/BF00327650

Abstract

The E. coli dnaX and dnaZ gene products, essential for E. coli DNA replication, serve in chain elongation. Both genes, located at 10.4 min and previously cloned into a lambda vector and a ColE1 plasmid, were subcloned into pBR322 (pMK212). The coding region for the dnaX and dnaZ genes was localized to a 2.2-kb segment by deletion analysis of pMK212. The products of dnaX and dnaZ genes were identified as 78 kd and 52 kd polypeptides, respectively, by using maxicells bearing deletion clones of pMK212. Peptide mapping after limited proteolysis showed that the dnaZ gene product (52 kd) is a part of the dnaX gene product (78 kd), thus accounting for the coding capacity of the 2.2 kb region for both the dnaX and dnaZ genes. The dnaX gene product appears to be the tau subunit of DNA polymerase III holoenzyme; the dnaZ gene product is confirmed as the gamma subunit of the holoenzyme.

摘要

大肠杆菌的dnaX和dnaZ基因产物对大肠杆菌DNA复制至关重要，它们参与链延长过程。这两个基因位于10.4分钟处，先前已被克隆到λ载体和ColE1质粒中，现在又被亚克隆到pBR322（pMK212）中。通过对pMK212进行缺失分析，将dnaX和dnaZ基因的编码区域定位到一个2.2 kb的片段上。利用携带pMK212缺失克隆的最大细胞，分别将dnaX和dnaZ基因的产物鉴定为78 kd和52 kd的多肽。有限蛋白酶解后的肽图分析表明，dnaZ基因产物（52 kd）是dnaX基因产物（78 kd）的一部分，因此解释了2.2 kb区域对dnaX和dnaZ基因的编码能力。dnaX基因产物似乎是DNA聚合酶III全酶的τ亚基；dnaZ基因产物被确认为全酶的γ亚基。