Baeza L, Bertrand A, Mache R, Lerbs-Mache S
Laboratoire de Biologie Moléculaire Végétale, Université Joseph Fourier, CNRS URA 1178, Grenoble, France.
Nucleic Acids Res. 1991 Jul 11;19(13):3577-81. doi: 10.1093/nar/19.13.3577.
By means of mobility-shift assays and Exonuclease III mapping we have determined a 14 bp sequence (named CDF2 binding site) located in front of the 16S rRNA initiation start site which is protected by a spinach chloroplast extract. This region does not include neither one of the two '-35' nor of the two '-10' E. coli-like promoter elements which are recognised by E. coli RNA polymerase in vitro. The CDF2 binding site is specifically recognized by two small polypeptides which migrate corresponding to 35 and 33 kDa respectively as shown by UV cross-linking experiments. In vivo transcription initiation of the 16S rRNA gene occurs 13 nucleotides downstream of the 14 bp sequence and is different from the transcription start site which is used by E.coli polymerase in vitro.
通过迁移率变动分析和核酸外切酶III图谱分析，我们确定了位于16S rRNA起始位点之前的一段14 bp序列（命名为CDF2结合位点），该序列能被菠菜叶绿体提取物保护。该区域既不包含两种“-35”元件中的任何一个，也不包含两种“-10”元件中的任何一个，这两种元件是大肠杆菌RNA聚合酶在体外识别的类似大肠杆菌的启动子元件。如紫外线交联实验所示，CDF2结合位点能被两种小多肽特异性识别，它们的迁移率分别对应35 kDa和33 kDa。16S rRNA基因在体内的转录起始发生在14 bp序列下游13个核苷酸处，与大肠杆菌聚合酶在体外使用的转录起始位点不同。
