EFFECT OF THE BACTERIAL-GROWTH RATE ON REPLICATION CONTROL OF PLASMID PBR322 IN ESCHERICHIA-COLI
EFFECT OF THE BACTERIAL-GROWTH RATE ON REPLICATION CONTROL OF PLASMID PBR322 IN ESCHERICHIA-COLI
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DOI：
10.1007/bf00330395
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发表时间：
1986-01-01
期刊：
影响因子：
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通讯作者：
BREMER, H
中科院分区：
文献类型：
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作者：
LINCHAO, S;BREMER, H
观察了pBR322复制抑制因子RNAi和预引物RNAII在大肠杆菌中的浓度与细菌生长速度的关系。在0.6~2.5倍/h的生长速度下，拷贝数(相当于染色体DNA的每个基因组的质粒数)从32个减少到15个，每个细胞的质粒数从39个增加到55个，质粒浓度从4.6倍下降到1.1倍。每单位OD460细胞质量含有1010个质粒。RNAi和RNAII的浓度也随着生长速度的增加而降低，但不同的是，它们的比值RNAi/RNAII增加。在甘油微量介质中，RNAi和RNAII具有相同的半衰期，为0.55min，其合成比例约为3个RNAi转录本/RNAII转录本。根据负对照模型对这些结果进行了解释，表明RNAi和RNAII启动子的活性以及RNAi抑制质粒复制的效率受到生长速度的控制。
The concentration of plasmid pBR322, of its replication inhibitor, RNAI, and preprimer, RNAII, were observed in E. coli as functions of the bacterial growth rate. At growth rates between 0.6 and 2.5 doubling/h, the copy number (number of plasmids per genome equivalent of chromosomal DNA) decreased from 32 to 15, the number of plasmids per cell increased from 39 to 55, and the plasmid concentration decreased from 4.6 to 1.1 .times. 1010 plasmids per OD460 unit of cell mass. The concentrations of RNAI and RNAII also decreased with increasing growth rate, but differently, such that their ratio, RNAI/RNAII, increased. In glycerol minimal medium both RNAI and RNAII had the same halflife, 0.55 min, and were synthesized at a ratio of about 3 RNAI transcripts per every RNAII transcript. These results were interpreted on the basis of the negative control model and suggest that the activities of the RNAI and RNAII promoters, and the efficiency with which RNAI inhibits plasmid replication, are controlled by the growth rate.