Does RNA polymerase help drive chromosome segregation in bacteria?
Does RNA polymerase help drive chromosome segregation in bacteria?
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DOI：
10.1073/pnas.182539899
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发表时间：
2002-10-29
影响因子：
11.1
通讯作者：
Losick, R
中科院分区：
文献类型：
--
作者：
Dworkin, J;Losick, R
与真核细胞不同，细菌分离它们的染色体时没有明显的有丝分裂装置。细菌染色体的复制是从单个位点(ORIC)双向启动的，对活细胞中含有ORIC的染色体区域的可视化表明，在细胞周期中，起源迅速向细胞的相反两极移动。驱动这一极地运动的马达尚不清楚。一个有吸引力的候选者是RNA聚合酶，它是一种强大而丰富的分子马达。如果像其他大分子复合体一样，RNA聚合酶在细胞中的运动受到限制，那么转录将移位DNA模板，从而提供分离复制染色体的动力。许多转录RNA聚合酶的协同效应可能是由于基因定位远离ORIC的广泛保守的全球偏向造成的。通过对活的枯草芽孢杆菌细胞的荧光显微镜观察，我们证明了RNA聚合酶的抑制剂可以抑制复制起点附近新复制的DNA的分离。我们认为，RNA聚合酶施加的力有助于细菌中的染色体运动，并且这种力，再加上转录单位的偏向，有助于推动染色体分离。
In contrast to eukaryotic cells, bacteria segregate their chromosomes without a conspicuous mitotic apparatus. Replication of bacterial chromosomes initiates bidirectionally from a single site (oriC), and visualization of the region of the chromosome containing oriC in living cells reveals that origins rapidly move apart toward opposite poles of the cell during the cell cycle. The motor that drives this poleward movement is unknown. An attractive candidate is RNA polymerase, which is a powerful and abundant molecular motor. If, as has been suggested for other macromolecular complexes, the movement of RNA polymerase is restricted in the cell, then transcription would translocate the DNA template, thereby providing the motive force to separate replicating chromosomes. A coordinated effect of many transcribing RNA polymerases could result from the widely conserved global bias of gene orientation away from oriC. By using fluorescence microscopy of living Bacillus subtilis cells, we demonstrate that an inhibitor of RNA polymerase acts to inhibit separation of newly duplicated DNAs near the origin of replication. We propose that the force exerted by RNA polymerase contributes to chromosome movement in bacteria, and that this force, coupled with the biased orientation of transcription units, helps to drive chromosome segregation.