Dartigalongue C, Missiakas D, Raina S
Departement de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, 1211 Geneva 4, Switzerland.
J Biol Chem. 2001 Jun 15;276(24):20866-75. doi: 10.1074/jbc.M100464200. Epub 2001 Mar 23.
Escherichia coli responds to the accumulation of misfolded proteins by inducing the transcription of heat shock genes. Efinal sigma(E) RNA polymerase controls one of the two heat shock regulons of E. coli. This regulon is activated upon accumulation of misfolded polypeptides in the double membrane envelope of E. coli. final sigma(E) (RpoE) is a member of the extracytoplasmic function subfamily of sigma factors. Here we asked how many genes are activated by Efinal sigma(E) RNA polymerase and what is the identity of these genes. Using two independent genetic approaches, 20 E. coli promoters were identified which activate reporter gene transcription in a final sigma(E)-dependent manner. In all cases examined, a canonical final sigma(E) binding site could be revealed upon mapping transcriptional start sites. 10 identified promoters activated the transcription of previously identified genes with four genes acting directly on the folding of E. coli envelope proteins (dsbC, fkpA, skp, and surA). The remaining promoters transcribed genes that are presumed to encode hitherto unknown extracytoplasmic functions and were named ecf (ecfA-ecfM). Two of these ecf genes were found to be essential for E. coli growth.
大肠杆菌通过诱导热休克基因的转录来应对错误折叠蛋白的积累。E终末σ（E）RNA聚合酶控制着大肠杆菌的两个热休克调节子之一。这个调节子在大肠杆菌双膜包膜中错误折叠多肽积累时被激活。E终末σ（E）（RpoE）是σ因子胞质外功能亚家族的成员。在这里，我们询问有多少基因被E终末σ（E）RNA聚合酶激活以及这些基因的身份是什么。使用两种独立的遗传学方法，鉴定出了20个大肠杆菌启动子，它们以E终末σ（E）依赖的方式激活报告基因转录。在所有检测的情况下，绘制转录起始位点时都能揭示出一个典型的E终末σ（E）结合位点。10个已鉴定的启动子激活了先前鉴定基因的转录，其中4个基因直接作用于大肠杆菌包膜蛋白的折叠（dsbC、fkpA、skp和surA）。其余的启动子转录的基因被推测编码迄今未知的胞质外功能，这些基因被命名为ecf（ecfA - ecfM）。发现其中两个ecf基因对大肠杆菌的生长至关重要。
