R质粒pEB017的特性，该质粒赋予大肠杆菌K12野生型、recA和umuC菌株增强的抗紫外线辐射能力和变异性。

Properties of R-plasmid pEB017, which confers both enhanced UV-radiation resistance and mutability to wild-type, recA and umuC strains of Escherichia coli K12.

作者信息

Obaseiki-Ebor E E, Smith K C

机构信息

Department of Radiation Oncology, Stanford University School of Medicine, CA 94305-5105.

出版信息

Mutat Res. 1992 May;267(1):67-76. doi: 10.1016/0027-5107(92)90111-e.

DOI:10.1016/0027-5107(92)90111-e

PMID:1373854

Abstract

The R-plasmid, pEB017, restored recombination ability to recA56 and conferred enhanced resistance to UV-radiation and enhanced UV-radiation mutability to wild-type, recA56 and umuC36 strains of Escherichia coli K12. Comparatively, pEB017 enhanced UV-radiation mutability in a umuC strain, and also enhanced UV-radiation and nitrofuran mutability in a wild-type strain several-fold more than did another R-plasmid, pKM101. Plasmid pEB017 also mediated about a 3-fold enhancement of the SOS induction of beta-galactosidase synthesis in a recA strain, compared with the normal recA+ gene of E. coli. A BamHI fragment of pEB017 DNA was cloned into plasmid vector pBR322 to yield pEB021. The BamHI fragment in pEB021 (3.5 kb) is about 170 bp longer between the BamHI and PstI sites on the left end of the recA-like fragment, compared with published data on a similarly cloned recA gene from E. coli. Plasmid pEB021 conferred enhanced resistance to UV-radiation and enhanced UV-radiation mutability in wild-type and recA strains, and restored recombination ability in a recA strain. The introduction of pEB021 into a umuC strain made the cells slightly more resistant to killing by UV-irradiation, and promoted a small amount of UV-mutability in an otherwise nonmutable strain. These results suggest that R-plasmid pEB017 has a recA-like gene that mediates the enhanced resistance to UV-radiation and enhanced UV-radiation mutability, but which seems different in several important aspects from the normal recA gene in E. coli.

摘要

R 质粒 pEB017 恢复了 recA56 的重组能力，并赋予大肠杆菌 K12 的野生型、recA56 和 umuC36 菌株增强的抗紫外线辐射能力以及增强的紫外线辐射诱变能力。相比之下，pEB017 增强了 umuC 菌株中的紫外线辐射诱变能力，并且与另一个 R 质粒 pKM101 相比，在野生型菌株中增强紫外线辐射和硝基呋喃诱变能力的倍数更高。与大肠杆菌的正常 recA⁺ 基因相比，质粒 pEB017 还介导 recA 菌株中 β-半乳糖苷酶合成的 SOS 诱导增强约 3 倍。将 pEB017 DNA 的 BamHI 片段克隆到质粒载体 pBR322 中，得到 pEB021。与已发表的来自大肠杆菌的类似克隆的 recA 基因的数据相比，pEB021 中的 BamHI 片段（3.5 kb）在 recA 样片段左端的 BamHI 和 PstI 位点之间长约 170 bp。质粒 pEB021 在野生型和 recA 菌株中赋予增强的抗紫外线辐射能力和增强的紫外线辐射诱变能力，并在 recA 菌株中恢复重组能力。将 pEB021 导入 umuC 菌株使细胞对紫外线照射的杀伤略有更强的抵抗力，并在原本不可诱变的菌株中促进了少量的紫外线诱变。这些结果表明，R 质粒 pEB017 具有一个 recA 样基因，该基因介导增强的抗紫外线辐射能力和增强的紫外线辐射诱变能力，但在几个重要方面似乎与大肠杆菌中的正常 recA 基因不同。