Tétart F, Albigot R, Conter A, Mulder E, Bouché J P
Centre de Recherche de Biochimie et de Génétique Cellulaires du CNRS, Toulouse, France.
Mol Microbiol. 1992 Mar;6(5):621-7. doi: 10.1111/j.1365-2958.1992.tb01509.x.
The cell-cycle parameters of an Escherichia coli strain expressing essential division gene ftsZ at one-fifth of its normal level, because of antisense regulation by DicF RNA, have been analysed. Inhibition of FtsZ expression affects neither the generation time nor the replication initiation mass, the C period, or the constriction period, but it does dramatically retard the initiation of constriction relative to replication termination. Separation of the nucleoids is equally postponed, indicating that division is not coupled to termination of replication, but to partitioning. The severe inhibition of nucleoid separation by DicF RNA, and its suppression by overproduction of FtsZ, suggest a role for FtsZ in the control of separation, and consequently in the coupling of separation and division. We suggest that the normal pattern of nucleoid separation previously found in cells deficient in ftsZ function was a consequence of the loss of a negative effect exerted by FtsZ on separation. In agreement with this view, we find that nucleoid separation is temporarily inhibited after arrest of FtsZ synthesis, but is later resumed as FtsZ is further diluted into the elongating filaments.
对一株大肠杆菌进行了细胞周期参数分析，该菌株由于DicF RNA的反义调控，其必需的分裂基因ftsZ的表达水平仅为正常水平的五分之一。FtsZ表达的抑制既不影响代时，也不影响复制起始质量、C期或缢缩期，但相对于复制终止，它确实显著延迟了缢缩的起始。类核的分离同样被推迟，这表明细胞分裂并非与复制终止相关联，而是与分配相关联。DicF RNA对类核分离的严重抑制以及过量表达FtsZ对其的抑制，表明FtsZ在分离控制中发挥作用，进而在分离与分裂的偶联中发挥作用。我们认为，先前在ftsZ功能缺陷的细胞中发现的类核分离的正常模式是FtsZ对分离施加的负面影响丧失的结果。与此观点一致，我们发现FtsZ合成停止后，类核分离会暂时受到抑制，但随着FtsZ进一步稀释到伸长的丝状体中，类核分离随后会恢复。
