Tang M S, Ross L
J Bacteriol. 1985 Mar;161(3):933-8. doi: 10.1128/jb.161.3.933-938.1985.
We transduced the uvrA6, uvrB5, uvrC34, and uvrC56 markers from the original mutagenized strains into an HF4714 background. Although in the original mutagenized strains uvrA6 cells are more UV sensitive than uvrB5 and uvrC34 cells, in the new background no significant difference in UV sensitivity is observed among uvrA6, uvrB5, and uvrC34 cells. No DNA single-strand breaks are detected in UV-irradiated uvrA6 or uvrB5 cells, whereas in contrast a significant number of single-strand breaks are detected in both UV-irradiated uvrC34 and uvrC56 cells. The number of single-strand breaks in these cells reaches a plateau at 20-J/m2 irradiation. Since these single-strand breaks can be detected by both alkaline sucrose and neutral formamide-sucrose gradient sedimentation, we concluded that the single-strand breaks observed in UV-irradiated uvrC cells are due to phosphodiester bond interruptions in DNA and are not due to apurinic/apyrimidinic sites.
我们将原始诱变菌株中的uvrA6、uvrB5、uvrC34和uvrC56标记导入HF4714背景中。虽然在原始诱变菌株中，uvrA6细胞比uvrB5和uvrC34细胞对紫外线更敏感，但在新背景下，uvrA6、uvrB5和uvrC34细胞之间未观察到紫外线敏感性的显著差异。在紫外线照射的uvrA6或uvrB5细胞中未检测到DNA单链断裂，而相比之下，在紫外线照射的uvrC34和uvrC56细胞中均检测到大量单链断裂。这些细胞中的单链断裂数量在20 J/m2照射时达到平台期。由于这些单链断裂可通过碱性蔗糖和中性甲酰胺 - 蔗糖梯度沉降检测到，我们得出结论，在紫外线照射的uvrC细胞中观察到的单链断裂是由于DNA中的磷酸二酯键中断，而非由于脱嘌呤/脱嘧啶位点。
