EastChem School of Chemistry and COSMIC, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3JR, UK.
Nucleic Acids Res. 2010 Jun;38(11):3721-31. doi: 10.1093/nar/gkq100. Epub 2010 Feb 25.
The AddAB helicase and nuclease complex is used for repairing double-strand DNA breaks in the many bacteria that do not possess RecBCD. Here, we show that AddAB, from the Gram-negative opportunistic pathogen Bacteroides fragilis, can rescue the ultraviolet sensitivity of an Escherichia coli recBCD mutant and that addAB is required for survival of B. fragilis following DNA damage. Using single-molecule observations we demonstrate that AddAB can translocate along DNA at up to 250 bp per second and can unwind an average of 14,000 bp, with some complexes capable of unwinding 40,000 bp. These results demonstrate the importance of processivity for facilitating encounters with recognition sequences that modify enzyme function during homologous recombination.
AddAB 解旋酶和核酸酶复合物用于修复许多不具有 RecBCD 的细菌中的双链 DNA 断裂。在这里，我们表明革兰氏阴性机会性病原体脆弱拟杆菌的 AddAB 可以挽救缺乏 RecBCD 的大肠杆菌突变体的紫外线敏感性，并且 AddAB 是脆弱拟杆菌在 DNA 损伤后存活所必需的。使用单分子观察，我们证明 AddAB 可以以每秒高达 250bp 的速度沿 DNA 转运，并可以解旋平均 14000bp，一些复合物能够解旋 40000bp。这些结果表明，在同源重组过程中，通过改变酶功能的识别序列进行促进酶与识别序列相遇的，需要具有较高的持续性。
