Identification of the HetR Recognition Sequence Upstream of hetZ in Anabaena sp Strain PCC 7120
Identification of the HetR Recognition Sequence Upstream of hetZ in Anabaena sp Strain PCC 7120
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DOI：
10.1128/jb.00119-12
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发表时间：
2012-05-01
影响因子：
3.2
通讯作者：
Xu, Xudong
中科院分区：
文献类型：
--
作者：
Du, Ye;Cai, Yan;Xu, Xudong
HetR是鱼腥藻菌株PCC 7120中异形胞分化的主要调节因子，并且已发现其特异性结合到异形胞分化基因hetP上游的含反向重复序列的区域。然而，在基因组中的其他基因的启动子中没有发现这样的反向重复序列。hetZ是一个参与早期异形胞分化的基因。如用gfp报告基因所示，来自P-hetZ的转录与hetR的表达水平和RGSGR（源自PatS的C末端的五肽）的抑制相关。电泳迁移率变动分析表明，重组HetR与hetZ上游区域特异性结合，且这种结合可被RGSGR抑制。一系列上游片段的测试将HetR结合位点界定为40 bp区域，该区域与hetP上游区域相似。在两个HetR结合位点中保守的碱基的取代的引入表明，至少需要12个碱基被HetR识别。含有HetR结合位点的51 bp区域的缺失完全消除了P-hetZ的转录活性。基于hetZ的HetR识别序列，提出了hetR和patA的上游识别序列。
HetR is the master regulator of heterocyst differentiation in Anabaena sp. strain PCC 7120 and has been found to specifically bind to an inverted-repeat-containing region upstream of hetP, a heterocyst differentiation gene. However, no such inverted-repeat sequence can be found in promoters of other genes in the genome. hetZ is a gene involved in early heterocyst differentiation. As shown with the gfp reporter gene, transcription from P-hetZ was correlated to the expression level of hetR and inhibition by RGSGR, the pentapeptide derived from the C terminus of PatS. As detected by electrophoretic mobility shift assay, a recombinant HetR showed specific binding to the region upstream of hetZ, and the binding was inhibited by RGSGR. Tests of a series of the upstream fragments delimited the HetR-binding site to a 40-bp region that shows similarity to that upstream of hetP. The introduction of substitutions of bases conserved in the two HetR-binding sites showed that at least 12 bases are required for recognition by HetR. Deletion of a 51-bp region containing the HetR-binding site completely eliminated the transcription activity of P-hetZ. Based on the HetR recognition sequence of hetZ, those upstream of hetR and patA are proposed.