Data_Sheet_4_Complete identity and expression of StfZ, the cis-antisense RNA to the mRNA of the cell division gene ftsZ, in Escherichia coli.PDF

Bacteria regulate FtsZ protein levels through transcriptional and translational mechanisms for proper cell division. A cis-antisense RNA, StfZ, produced from the ftsA-ftsZ intergenic region, was proposed to regulate FtsZ level in Escherichia coli. However, its structural identity remained unknown. In this study, we determined the complete sequence of StfZ and identified the isoforms and its promoters. We find that under native physiological conditions, StfZ is expressed at a 1:6 ratio of StfZ:ftsZ mRNA at all growth phases from three promoters as three isoforms of 366, 474, and 552 nt RNAs. Overexpression of StfZ reduces FtsZ protein level, increases cell length, and blocks cell division without affecting the ftsZ mRNA stability. We did not find differential expression of StfZ under the stress conditions of heat shock, cold shock, or oxidative stress, or at any growth phase. These data indicated that the cis-encoded StfZ antisense RNA to ftsZ mRNA may be involved in the fine tuning of ftsZ mRNA levels available for translation as per the growth-phase-specific requirement at all phases of growth and cell division.

细菌通过转录与翻译调控机制，精准调节FtsZ蛋白（FtsZ protein）的水平，以保障正常的细胞分裂。从ftsA-ftsZ基因间区转录产生的顺式反义RNA（cis-antisense RNA）StfZ，曾被认为可在大肠杆菌（Escherichia coli）中调控FtsZ蛋白的表达水平。然而此前其结构特征始终未被阐明。本研究中，我们完成了StfZ的全序列测定，并鉴定出其转录本亚型与启动子。我们发现，在天然生理条件下，StfZ由3个启动子转录，在所有生长阶段均以3种转录本亚型（长度分别为366、474和552 nt）的形式表达，且StfZ与ftsZ mRNA的表达量比值为1:6。过量表达StfZ会降低FtsZ蛋白的表达水平，使菌体长度增加，并阻断细胞分裂，但不会影响ftsZ mRNA的稳定性。我们未在热激、冷激或氧化应激等胁迫条件下，或是在任意生长阶段中检测到StfZ的差异表达。上述数据表明，靶向ftsZ mRNA的顺式编码反义RNA StfZ，可能在所有生长与细胞分裂阶段中，根据生长阶段的特定需求，对可用于翻译的ftsZ mRNA水平进行精细调控。