Utsumi R, Kusafuka S, Nakayama T, Tanaka K, Takayanagi Y, Takahashi H, Noda M, Kawamukai M
Department of Agricultural Chemistry, Kinki University, Nara, Japan.
FEMS Microbiol Lett. 1993 Nov 1;113(3):273-8. doi: 10.1111/j.1574-6968.1993.tb06526.x.
The fic gene, near pabA located at 75 min of the Escherichia coli chromosome, was previously identified as the regulatory factor of cell division. In this paper we have examined how fic gene expression is controlled during the growth cycle using a fic-lacZ protein fusion plasmid (pFL1). Its expression was induced at stationary phase while it was nearly abolished in rpoSmutants. Using a RNase protection assay, fic transcript at stationary phase was detected in rpoS+ strains, but not in the rpoS mutants. Furthermore, primer extension analysis indicated that the fic transcript controlled by RpoS initiates at a G located 185 bp upstream from ATG of the fic coding region. Compared with the sigma 70 recognition sequence, the -10 region of fic promoter resembled the Pribnow box, but no homologous sequence was observed at the -35 region. These results were consistent with the characteristic sequence profile of fic promoter recognized specifically by RpoS in vitro, which is the only example of the type III promoter so far detected in vitro and in vivo.
fic基因位于大肠杆菌染色体75分钟处，靠近pabA基因，先前被鉴定为细胞分裂的调节因子。在本文中，我们使用fic - lacZ蛋白融合质粒（pFL1）研究了fic基因在生长周期中的表达是如何被调控的。其表达在稳定期被诱导，而在rpoS突变体中几乎被消除。使用核糖核酸酶保护试验，在rpoS +菌株的稳定期检测到fic转录本，但在rpoS突变体中未检测到。此外，引物延伸分析表明，由RpoS调控的fic转录本从fic编码区ATG上游185 bp处的一个G开始。与sigma 70识别序列相比，fic启动子的 - 10区类似于Pribnow框，但在 - 35区未观察到同源序列。这些结果与体外特异性识别fic启动子的特征序列谱一致，这是迄今为止在体外和体内检测到的III型启动子的唯一例子。
