Rebollo J E, François V, Louarn J M
Centre de Biochimie et de Génétique Cellulaires du Centre National de la Recherche Scientifique, Toulouse, France.
Proc Natl Acad Sci U S A. 1988 Dec;85(24):9391-5. doi: 10.1073/pnas.85.24.9391.
Inversion of many predetermined segments of the Escherichia coli chromosome was attempted by using a system for in vivo selection of genomic rearrangements. Two types of constraints on these inversions were observed: (i) a sensitivity to rich medium when the distance between oriC and the 86- to 91-min region (which carries loci essential for transcription and translation) is increased; (ii) a poor viability or inviability of inversions having at least one endpoint in the one-third of the chromosome around replication terminators (with an exception for some inversions ending between these terminators). Although the first constraint is simply explained by a decreased dosage of the region involved, the second one may result from disruption of two long-range chromosomal organizations. The nondivisible zones thus disclosed coincide remarkably well with the two zones that we have previously described, which are polarized with respect to their replication. It is proposed that the two phenomena result from a sequence-dependent and polarized organization of the terminal region of the chromosome, which defines chromosome replication arms and may participate in nucleoid organization.
利用一种用于体内基因组重排选择的系统，尝试对大肠杆菌染色体的许多预定片段进行倒位。观察到这些倒位存在两种限制：（i）当oriC与86至91分钟区域（该区域携带转录和翻译所必需的基因座）之间的距离增加时，对丰富培养基敏感；（ii）在复制终止子周围染色体的三分之一区域中，至少有一个端点的倒位具有较差的活力或无法存活（某些在这些终止子之间结束的倒位除外）。虽然第一个限制可以简单地用所涉及区域的剂量减少来解释，但第二个限制可能是由于两个长程染色体组织的破坏。由此揭示的不可分割区域与我们之前描述的两个区域非常吻合，这两个区域在复制方面是极化的。有人提出，这两种现象是由染色体末端区域的序列依赖性和极化组织导致的，该组织定义了染色体复制臂，并可能参与类核组织。
