Effect of controlled expression of the hetR gene on heterocyst formation in the filamentous cyanobacterium Anabaena sp PCC 7120
Effect of controlled expression of the hetR gene on heterocyst formation in the filamentous cyanobacterium Anabaena sp PCC 7120
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DOI：
10.1034/j.1399-3054.2003.00108.x
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发表时间：
2003-09-01
影响因子：
6.4
通讯作者：
Kleiner, D
中科院分区：
文献类型：
--
作者：
El-Shehawy, RM;Kleiner, D
hetR是丝状蓝藻诱导并可能维持不可逆异囊分化的中心调控基因。构建了一个质粒，使iptg介导的p（tac）启动子的hetR可控表达成为可能。当引入缺乏杂泡的hetR突变体时，诱导导致在无组合氮的培养基中大量形成杂泡。在含硝酸盐的培养中，诱导只引起少数异囊的形成，但在营养细胞中导致氮黄化，这从藻胆蛋白的降解中可以看出。在无硝酸盐培养基中去除诱导剂IPTG可引起生物的黄化和死亡，但未逆转杂种囊的形成。这表明HetR的持续合成并不是异囊形成不可逆性的（唯一）原因。
hetR is a central regulatory gene inducing and possibly maintaining irreversible heterocyst differentiation in filamentous cyanobacteria. A plasmid was constructed which enabled IPTG-mediated, controlled expression of hetR from a p(tac) promoter in Anabaena. When introduced into a heterocyst-deficient hetR mutant, induction led to massive formation of heterocysts in a medium free of combined nitrogen. In nitrate-containing cultures, induction elicited formation of only a few heterocysts, but led to nitrogen chlorosis in vegetative cells as evidenced from degradation of phycobiliproteins. Removal of the inducer IPTG caused chlorosis and death of the organisms in nitrate-free medium, but no reversal of heterocyst formation. This indicates that constant synthesis of HetR is not the (sole) reason for irreversibility of heterocyst formation.