Coote J G, Binnie C
J Gen Microbiol. 1986 Feb;132(2):481-92. doi: 10.1099/00221287-132-2-481.
Mutations which allow tolerance to 5-bromo-2'-deoxyuridine (BUdR) in a thymidine (TdR)-requiring strain of Bacillus subtilis have been examined. Differences in sensitivity to BUdR existed between isogenic strains harbouring the mutations. Those mutations originally isolated as BUdR-tolerant also bestowed tolerance to 5-bromouracil and vice versa. The strain exhibiting the greatest tolerance to BUdR maintained a normal rate of replication in the presence of BUdR whereas the parent strain did not, but the tolerant strain incorporated less analogue into DNA than the parent strain. The basis of the tolerance mutation appeared to lie at the point of uptake of the analogue into the cell as the tolerant mutant preferentially took up TdR over BUdR into whole cells. DNA polymerase activity measured in vitro did not distinguish between TdR and BUdR in either the parent or the mutant strain and although TdR kinase activity showed a preference for TdR over BUdR as a substrate, the extent of discrimination was similar in both strains.
对枯草芽孢杆菌胸腺嘧啶核苷（TdR）需求菌株中允许对5-溴-2'-脱氧尿苷（BUdR）产生耐受性的突变进行了研究。携带这些突变的同基因菌株对BUdR的敏感性存在差异。最初作为对BUdR耐受而分离出的那些突变也赋予了对5-溴尿嘧啶的耐受性，反之亦然。对BUdR表现出最大耐受性的菌株在存在BUdR的情况下维持正常的复制速率，而亲本菌株则不然，但耐受菌株比亲本菌株将更少的类似物掺入DNA中。耐受性突变的基础似乎在于类似物进入细胞的摄取点，因为耐受突变体在全细胞中优先摄取TdR而非BUdR。在体外测量的DNA聚合酶活性在亲本菌株或突变菌株中都无法区分TdR和BUdR，并且尽管TdR激酶活性显示出对TdR作为底物的偏好超过BUdR，但在两种菌株中的区分程度相似。
