Osmotic regulation of the Streptomyces lividans thiostrepton-inducible promoter, ptipA
Osmotic regulation of the Streptomyces lividans thiostrepton-inducible promoter, ptipA
复制标题
DOI：
10.1099/00221287-148-2-381
复制
发表时间：
2002-02-01
期刊：
影响因子：
2.8
通讯作者：
Dyson, PJ
中科院分区：
文献类型：
--
作者：
Ali, N;Herron, PR;Dyson, PJ
lividans链霉菌中硫链蛋白诱导启动子ptipA的转录激活由TipAL介导。该转录激活因子属于MerR/SoxR家族，其特征是结合位于-10和-35六聚体之间的操作符序列，通常由RNA聚合酶占据。至于大肠杆菌merT启动子，ptipA六聚体被一条19 bp的间隔分隔开，因此DNA的拓扑转移可能是与RNA聚合酶对齐的必要条件。利用ptipA与报告基因的转录融合研究了促进这种构象变化的生长条件。调节生长介质渗透压导致tipal依赖性表达增加和延长，无论是否有诱导剂硫链霉素。这些影响与负DNA超卷曲的增加有关。此外，在菌株TK64中，不能用硫链蛋白诱导启动子是通过增加渗透液浓度来纠正的，补偿了菌株中明显降低的负DNA超卷曲水平。通过调节生长条件延长野生型tipA的激活时间，发现硫链霉素可以诱导4 d培养的菌丝自溶。
Transcriptional activation of the thiostrepton-inducible promoter, ptipA, in Streptomyces lividans is mediated by TipAL. This transcriptional activator belongs to the MerR/SoxR family that characteristically binds an operator sequence located between the -10 and -35 hexamers normally occupied by RNA polymerase. As for the Escherichia coli merT promoter, the ptipA hexamers are separated by along 19 bp spacer and hence a topological transition of the DNA is likely to be a requisite for alignment with RNA polymerase. Growth conditions that could facilitate this conformational change were investigated using transcriptional fusions of ptipA with reporter genes. Adjustment of growth medium osmolarity led to increased and prolonged TipAL-dependent expression, both with and without the inducer, thiostrepton. These effects correlated with increases in negative DNA supercoiling. Moreover, an inability to induce the promoter with thiostrepton in strain TK64 was corrected by increasing the concentration of osmolyte, compensating for an apparent reduced level of negative DNA supercoiling in the strain. Prolonging the time of activation of tipA in the wild-type by manipulating growth conditions revealed that mycelial autolysis could be induced by thiostrepton in 4-d-old cultures.