鱼腥蓝细菌PCC 7120 中一个受到NtcA调控的基因alr1390

A putative NtcA-regulating gene, alr1390, in Anabaena sp. PCC 7120

摘要:

摘要： NtcA是鱼腥蓝细菌中一种重要的氮代谢调控蛋白质，参与异形胞的分化。许多受NtcA调控的基因都至少有一个保守的NtcA结合位点GTA-N8-TAC。经生物信息学分析，鱼腥蓝细菌PCC 7120 基因alr1390可能的转录起始位点的上游有一个保守的NtcA结合位点GTA-TAG TTTTC-TAC。【目的】为了鉴定alr1390和NtcA之间的关系，【方法】采用实时定量反转录PCR实验（Real-time RT-PCR）和电泳迁移率实验（Electrophoretic mobility shift assays, EMSA）对alr1390和NtcA之间的关系进行了分析。【结果】Real-time RT-PCR结果显示，alr1390的转录水平在野生型鱼腥蓝细菌PCC 7120中缺氮诱导后和诱导前持平，而在ntcA突变体中缺氮诱导12h后呈现上调趋势。但是EMSA实验中没有检测到明显的NtcA和alr1390启动子区片段结合的滞后带，却观察到一条拖带。【结论】这说明alr1390受到NtcA的调控。

Abstract:

Abstract: NtcA is a master transcriptional regulator in global nitrogen control in Anabaena. Heterocyst differentiation depends on the NtcA protein. A large number of genes regulated by NtcA have a consensus sequence, GTA-N8-TAC, for NtcA binding. Bioinformatics analysis of alr1390 in the chromosome of Anabaena sp. PCC 7120 indicates that there is a conservative NtcA binding box, GTA-TAGTTTTC-TAC, upstream the putative tsp position of alr1390. [Objective] To understand the relationship between alr1390 and NtcA, [Methods] Real-time RT-PCR and EMSA were used. [Results] Real-time RT-PCR results showed that the transcriptional level of alr1390 remained constant before and after combined nitrogen step-down in wild type Anabaena sp. PCC 7120. However, in the ntcA mutant, there was an increase in the transcriptional level of alr1390 after 12h of combined nitrogen step-down, which indicated that alr1390 should be subject to the regulation of NtcA. Additionally although no conspicuous NtcA-alr1390 complex was detected by EMSA in vitro, a smear appeared in gel electrophoresis. [Conclusion] These results suggested that alr1390 might be regulated by NtcA.