Kölling R, Gielow A, Seufert W, Kücherer C, Messer W
Max-Planck-Institut für molekulare Genetik, Berlin.
Mol Gen Genet. 1988 Apr;212(1):99-104. doi: 10.1007/BF00322450.
The expression of the gidA gene which is located immediately counterclockwise of the replication origin of Escherichia coli, oriC, was found to be negatively regulated by the AsnC protein in an in vitro transcription-translation system. This effect is not due to simple repression of transcription originating at the gidA promoter, because the AsnC protein did not change the level of gidA promoter dependent transcription as analysed by promoter-galK fusions and by S1 mapping. From these data we conclude that the AsnC protein controls gidA gene expression at a post-transcriptional level. gidA is the third gene in the oriC region, besides asnA and asnC, whose expression is under AsnC control. However, the mechanisms involved are different: regulation of transcription in the case of asnA and asnC and post-transcriptional control of gidA. The gidA promoter was mapped by deletion analysis and by S1 mapping. We defined two regions that affect promoter activity negatively. Additional transcripts, regulated by AsnC, started more than 300 bp upstream of the gidA promoter and were found to enter the gidA region. These transcripts, originating either at the mioC and/or the ansC promoter traverse the replication origin.
位于大肠杆菌复制起点oriC逆时针方向紧邻位置的gidA基因的表达，在体外转录-翻译系统中被AsnC蛋白负调控。这种效应并非源于对gidA启动子起始转录的简单抑制，因为通过启动子-galK融合和S1作图分析发现，AsnC蛋白并未改变gidA启动子依赖性转录的水平。从这些数据我们得出结论，AsnC蛋白在转录后水平控制gidA基因的表达。gidA是oriC区域中除asnA和asnC之外第三个其表达受AsnC控制的基因。然而，所涉及的机制不同：asnA和asnC的情况是转录调控，而gidA是转录后控制。通过缺失分析和S1作图确定了gidA启动子的位置。我们确定了两个对启动子活性有负向影响的区域。受AsnC调控的其他转录本起始于gidA启动子上游300多个碱基对处，并发现它们进入gidA区域。这些转录本要么起始于mioC和/或ansC启动子，它们会穿过复制起点。
