野生型变铅青链霉菌具有一种不同于甲基化修饰的新型DNA硫修饰系统,使DNA在电泳时易遭到氧化双链切割而导致降解(Dnd, DNA degradation)表型(Zhou et al., 1988, 1994, 1999)。己证实该菌株染色体上一段8.3kb的区域与Dnd表型有关,序列分析显示该区域包含了3个ORFs—dndA, dndB和dndC(Zhou et al., 1999;李爱英,2000)。为了验证这三个基因与Dnd表型的关系,构建了一系列衍生于整合型载体pSET152的质粒:pHZ2150,pHZ2151,pHZ2152和pHZ2153。它们均携带包含3个ORFs的区域(除了pHZ2153在dndB和dndC内缺失了2kb),但已分别在各ORF上发生单基因中断(pHZ2150,pHZ2151和pHZ2152上外源片段的中断分别发生在dndA,月和C上)。将它们导入Dnd表型缺失突变株ZX1中进行基因互补实验,结果证明变铅青链霉菌and基因簇上的3个ORFs均为Dnd所必需。
对野生型变铅青链霉菌dnd基因簇的生物学功能进行了初步探索。以野生型...
【英文摘要】
A novel DNA modification discovered in Streptomyces lividans 1326 is different from DNA methylation. This unusual modification causes wild type S. lividans 1326 DNA sensitive to site-specific oxidative double-strand cleavage (Dnd phenotype). Preliminary study revealed that such DNA modification involves incorporation of sulphur. The entire functional dnd cluster, 8.3kb in size, including 3 ORFs-dndA, dndB and dndC was involved in this DNA modification. Four plasmids derived from an integrative v...