Enhancement of the synthesis of RpoN, Cra, and H-NS by polyamines at the level of translation in Escherichia coli cultured with glucose and glutamate
Enhancement of the synthesis of RpoN, Cra, and H-NS by polyamines at the level of translation in Escherichia coli cultured with glucose and glutamate
复制标题
DOI：
10.1128/jb.01562-06
复制
发表时间：
2007-03-01
影响因子：
3.2
通讯作者：
Igarashi, Kazuei
中科院分区：
文献类型：
--
作者：
Terui, Yusuke;Higashi, Kyohei;Igarashi, Kazuei
在0.1%葡萄糖和0.02%谷氨酸代替0.4%葡萄糖作为能源的存在下培养的需要多胺的突变体中，鉴定了其合成在翻译水平上被多胺增强的蛋白质。在这些条件下，多胺对细胞生长的促进作用与0.4%葡萄糖的作用几乎相同。发现在生长的对数期早期，多胺在翻译水平上增强了RpoN、Cra和H-NS的合成（A（540）为0.15）。多胺对RpoN、H-NS和Cra合成的影响是由于其mRNA中存在不寻常的Shine-Dalgarno序列（RpoN和H-NS）和无效的GUG起始密码子（Cra）。因此，rpoN，cra和hns基因被确定为多胺调节子的新成员。因为迄今为止鉴定的大多数多胺调节子基因编码转录因子（RpoS [sigma（38）]、Cya、FecI [sigma（18）]、Fis、RpoN [sigma（54）]、Cra和H-NS），所以进行细胞中表达的mRNA的DNA微阵列分析。在对数生长期的早期，总共有97种被多胺上调超过两倍的mRNA受到上述7个多胺调节子基因的控制。
Proteins whose synthesis is enhanced by polyamines at the level of translation were identified in a polyamine-requiring mutant cultured in the presence of 0.1% glucose and 0.02% glutamate instead of 0.4% glucose as an energy source. Under these conditions, enhancement of cell growth by polyamines was almost the same as that in the presence of 0.4% glucose. It was found that synthesis of RpoN, Cra, and H-NS was enhanced by polyamines at the level of translation at the early logarithmic phase of growth (A(540) of 0.15). The effects of polyamines on synthesis of RpoN, H-NS, and Cra were due to the existence of unusual Shine-Dalgarno sequences (RpoN and H-NS) and an inefficient GUG initiation codon (Cra) in their mRNAs. Thus, rpoN, cra, and hns genes were identified as new members of the polyamine modulon. Because most of the polyamine modulon genes thus far identified encode transcription factors (RpoS [sigma(38)], Cya, FecI [sigma(18)], Fis, RpoN [sigma(54)], Cra, and H-NS), DNA microarray analysis of mRNA expressed in cells was performed. At the early logarithmic phase of growth, a total of 97 species of mRNAs that were up-regulated by polyamines more than twofold were under the control of seven polyamine modulon genes mentioned above.