MOLECULAR MECHANISM FOR THE OPERATION OF NITROGEN CONTROL IN CYANOBACTERIA
MOLECULAR MECHANISM FOR THE OPERATION OF NITROGEN CONTROL IN CYANOBACTERIA
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DOI：
10.1002/j.1460-2075.1994.tb06580.x
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发表时间：
1994-06-15
期刊：
影响因子：
11.4
通讯作者：
HERRERO, A
中科院分区：
文献类型：
--
作者：
LUQUE, I;FLORES, E;HERRERO, A
在蓝细菌中，铵对参与氮源替代铵同化的蛋白质的表达产生负调节。在聚球藻属中，硝酸盐和铵同化的编码蛋白质的基因的mRNA水平被观察到由铵负调控，并且确定了这些基因的铵调控转录起始点。NtcA蛋白是受铵氮控制的基因的正调控因子。缺乏NtcA的突变体仅表现出基础mRNA水平的调节基因，即使在没有铵，表明NtcA发挥其调节作用，通过积极影响氮调节基因的mRNA水平。观察到NtcA直接与氮调节基因的启动子结合，并且回文DNA序列GTAN（8）TAC被鉴定为NtcA靶位点的序列特征。聚球藻的氮调控启动子和NtcA调控启动子的结构被确定为由TAN（3）T形式的-10，Pribnow样盒和取代典型-35盒的NtcA结合位点构成。
In cyanobacteria, ammonium exerts a negative regulation of the expression of proteins involved in the assimilation of nitrogen sources alternative to ammonium. In Synechococcus, mRNA levels of genes encoding proteins for nitrate and ammonium assimilation were observed to be negatively regulated by ammonium, and ammonium-regulated transcription start points were identified for those genes. The NtcA protein is a positive regulator of genes subjected to nitrogen control by ammonium. Mutants lacking NtcA exhibited only basal mRNA levels of the regulated genes, even in the absence of ammonium, indicating that NtcA exerts its regulatory action by positively influencing mRNA levels of the nitrogen-regulated genes. NtcA was observed to bind directly to the promoters of nitrogen-regulated genes, and the palindromic DNA sequence GTAN(8)TAC was identified as a sequence signature for NtcA-target sites. The structure of the nitrogen-, NtcA-regulated promoters of Synechococcus was determined to be constituted by a -10, Pribnow-like box in the form TAN(3)T, and an NtcA-binding site that substituted for the canonical -35 box.