Expression of two alternative sigma factors of Synechococcus sp. strain PCC 7002 is modulated by carbon and nitrogen stress
Expression of two alternative sigma factors of Synechococcus sp. strain PCC 7002 is modulated by carbon and nitrogen stress
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DOI：
10.1099/00221287-143-12-3807
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发表时间：
1997-12-01
期刊：
影响因子：
2.8
通讯作者：
Bryant, DA
中科院分区：
文献类型：
--
作者：
Caslake, LF;Gruber, TM;Bryant, DA
sigB和sigC基因，编码两个替代西格玛因子的单细胞海洋蓝藻聚球藻属PCC 7002，克隆和表征。其中sigB和sigC基因被插入失活的菌株在标准实验室条件下是活的，表明SigB和SigC是2组西格玛因子。无论是氮或碳饥饿引起sigB mRNA水平的增加。sigC基因的转录本最初增加，但随后下降，在氮和碳饥饿。使用来自枯草芽孢杆菌的聚球藻属PCC 7002 SigA或RpoD的抗血清不能在蓝藻提取物中鉴定SigC蛋白。在氮饥饿或碳饥饿期间，主要营养西格玛因子SigA与SigB的比率下降，SigB的水平也在sigC突变株中增加。这些结果意味着SigB和SigC在响应于该蓝藻中碳和氮可用性的变化而修改转录中起作用。
The sigB and sigC genes, encoding two alternative sigma factors of the unicellular marine cyanobacterium Synechococcus sp. PCC 7002, were cloned and characterized. Strains in which the sigB and sigC genes were insertionally inactivated were viable under standard laboratory conditions, indicating that SigB and SigC are group 2 sigma factors. Starvation for either nitrogen or carbon caused an increase in sigB mRNA levels. Transcripts for the sigC gene initially increased but then decreased during nitrogen and carbon starvation. The SigC protein could not be identified in cyanobacterial extracts using antisera to Synechococcus sp. PCC 7002 SigA or RpoD from Bacillus subtilis. The ratio of the principal vegetative sigma factor, SigA, to SigB decreased during either nitrogen starvation or carbon starvation, and the levels of SigB also increased in the sigC mutant strain. These results imply that SigB and SigC play roles in modifying transcription in response to changes in carbon and nitrogen availability in this cyanobacterium.