在荚膜红细菌中，CIRCE不参与groESL的热依赖性转录，而是参与mRNA 5'端的稳定。
CIRCE is not involved in heat-dependent transcription of groESL but in stabilization of the mRNA 5'-end in Rhodobacter capsulatus.
作者信息
Jäger Stephanie, Jäger Andreas, Klug Gabriele
机构信息
Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 26, D-35392 Giessen, Germany.
出版信息
Nucleic Acids Res. 2004 Jan 16;32(1):386-96. doi: 10.1093/nar/gkh174. Print 2004.
The CIRCE element, an inverted DNA repeat, is known to be involved in the temperature-dependent regulation of genes for heat shock proteins in a variety of organisms. The CIRCE element was identified as the target for the HrcA protein, which represses transcription of heat shock genes under normal growth temperature. Our data reveal that the CIRCE element is not involved in the temperature-dependent transcription of the groESL genes in Rhodobacter capsulatus. Apparently, R.capsulatus does not harbour an HrcA protein. The mechanisms of heat shock regulation of the groESL genes in R.capsulatus therefore diverge significantly from the regulatory pathway identified in other organisms. A structural analysis of the CIRCE RNA element revealed a stem of 11 nt pairs and a loop of only 5 nt. This folding differs from a structure with a 9 nt loop suggested previously on the basis of computer analysis. The RNA structure leads to a slight stabilization of the groESL mRNA that is more pronounced at normal growth temperature than under heat shock conditions.
CIRCE元件是一种反向DNA重复序列，已知它参与多种生物体中热休克蛋白基因的温度依赖性调控。CIRCE元件被确定为HrcA蛋白的作用靶点，HrcA蛋白在正常生长温度下抑制热休克基因的转录。我们的数据表明，CIRCE元件不参与荚膜红细菌中groESL基因的温度依赖性转录。显然，荚膜红细菌不含HrcA蛋白。因此，荚膜红细菌中groESL基因的热休克调控机制与其他生物体中确定的调控途径有显著差异。对CIRCE RNA元件的结构分析揭示了一个由11个核苷酸对组成的茎和一个仅由5个核苷酸组成的环。这种折叠与之前基于计算机分析提出的具有9个核苷酸环的结构不同。RNA结构导致groESL mRNA略有稳定，在正常生长温度下比在热休克条件下更明显。
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