Qi H, Menzel R, Tse-Dinh Y C
Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla 10595, USA.
FEMS Microbiol Lett. 1999 Sep 1;178(1):141-6. doi: 10.1111/j.1574-6968.1999.tb13770.x.
An Escherichia coli mutant with three of the promoters for the topoisomerase I gene (topA) deleted, such that only the sigma 32-dependent promoter (P1) remained, had a decreased level of topoisomerase I at 30 degrees C and showed increased thermosensitivity at 52 degrees C. However, it could still develop thermotolerance and had a wild-type level of resistance to 52 degrees C treatment if exposed first to 42 degrees C. This indicated that newly synthesized topoisomerase I from transcription initiated at P1 was important for development of thermotolerance. Two other E. coli mutants lacking topA were > 100 times more sensitive to high temperature than their wild-type isogenic strains.
一种大肠杆菌突变体，其拓扑异构酶I基因（topA）的三个启动子被删除，以至于仅剩下依赖σ32的启动子（P1），该突变体在30℃时拓扑异构酶I水平降低，在52℃时表现出更高的热敏感性。然而，如果先暴露于42℃，它仍能产生热耐受性，并且对52℃处理具有野生型水平的抗性。这表明从P1启动转录新合成的拓扑异构酶I对热耐受性的产生很重要。另外两个缺失topA的大肠杆菌突变体对高温的敏感性比其野生型同基因菌株高100倍以上。
