TRANSCRIPTION MAPPING OF THE ESCHERICHIA-COLI CHROMOSOME BY ELECTRON-MICROSCOPY
TRANSCRIPTION MAPPING OF THE ESCHERICHIA-COLI CHROMOSOME BY ELECTRON-MICROSCOPY
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DOI：
10.1128/jb.171.8.4207-4216.1989
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发表时间：
1989-08-01
影响因子：
3.2
通讯作者：
MILLER, OL
中科院分区：
文献类型：
--
作者：
FRENCH, SL;MILLER, OL
电子显微镜观察到的rRNA操纵子独特的双圣诞树形态使它们很容易在大肠杆菌的染色质扩散中识别。根据附近转录单位上新生转录物的模式以及操纵子彼此之间和复制起点之间的相对距离，我们现在能够特异性地鉴定E.杆菌rRNA操纵子作为位置和距离的标记物的使用导致了E.大肠杆菌染色体;现在可以识别84- 90-min和72-min区域中的600多个酶对。由于可以鉴定单个rRNA操纵子，因此可以对其转录活性进行直接比较。通过RNA聚合酶沿着操纵子的密度判断，rrnA、rrnB、rrnC、rrnD和rrnE都以相似的水平转录，每85个碱基对就有一个RNA聚合酶。识别单个操纵子和染色体特定区域的能力允许直接比较各种遗传参数。
The distinctive double Christmas tree morphology of rRNA operons as visualized by electron microscopy makes them easy to recognize in chromatin spreads from Escherichia coli. On the basis of the pattern of nascent transcripts on nearby transcription units and the relative distances of the operons from one another and the replication origin, we are now able to specifically identify five of the seven rRNA operons in E. coli. The use of rRNA operons as markers of both position and distance has resulted in the morphological mapping of a significant portion of the E. coli chromosome; over 600 kilobase pairs in the 84- to 90-min and 72-min regions can now be recognized. Since individual rRNA operons could be identified, direct comparisons could be made of their transcriptional activities. As judged by the densities of RNA polymerases along the operons, rrnA, rrnB, rrnC, rrnD, and rrnE were all transcribed at similar levels, with one RNA polymerase every 85 base pairs. The ability to recognize individual operons and specific regions of the chromosome allows direct comparisons of various genetic parameters.