豌豆根瘤菌中Hfq和RNase E复合物对NifA表达的转录后调控
Post-transcriptional regulation of NifA expression by Hfq and RNase E complex in Rhizobium leguminosarum bv. viciae.
作者信息
Zhang Yinghua, Hong Guofan
机构信息
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
出版信息
Acta Biochim Biophys Sin (Shanghai). 2009 Sep;41(9):719-30. doi: 10.1093/abbs/gmp060.
NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum bv. viciae strain 8401/pRL1JI, the NifA gene is part of a gene cluster (fixABCXNifAB). In this study, results showed that in R. leguminosarum bv.viciae 8401/pRL1JI, host factor required (Hfq), and RNase E were involved in the post-transcriptional regulation of NifA expression. It was found that Hfq-dependent RNase E cleavage of NifA mRNA was essential for NifA translation. The cleavage site is located at 32 nucleotides upstream of the NifA translational start codon. A possible explanation based on predicted RNA secondary structure of the NifA 5'-untranslated region was that the cleavage made ribosome-binding sites accessible for translation.
NifA是固氮细菌中固氮基因的一般转录激活因子。在豌豆根瘤菌蚕豆生物型8401/pRL1JI菌株中，NifA基因是一个基因簇（fixABCXNifAB）的一部分。在本研究中，结果表明，在豌豆根瘤菌蚕豆生物型8401/pRL1JI中，宿主因子Hfq和核糖核酸酶E参与了NifA表达的转录后调控。研究发现，Hfq依赖的核糖核酸酶E对NifA mRNA的切割对于NifA的翻译至关重要。切割位点位于NifA翻译起始密码子上游32个核苷酸处。基于NifA 5'非翻译区预测的RNA二级结构的一种可能解释是，切割使核糖体结合位点可用于翻译。
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