摘要
大肠杆菌细胞染色体上毒素-抗毒素系统(TA,toxin-antitoxinsystem)基因参与环境胁迫诱导的细胞死亡或生长抑制。在蓝细菌PCC6803染色体上开放阅读框ssr1114和slr0664具有与TA系统相同的遗传结构,slr0664编码产物与RelBE毒素-抗毒素系统中的毒素蛋白RelE同源,但没有发现有与ssr1114编码产物同源的蛋白。为证明slr0664和ssr1114表达产物的毒性和抗毒性作用,构建了含有乳糖诱导调控的启动子和阿拉伯糖诱导调控的启动子的表达调控系统,将slr0664基因编码序列置于Plac启动子控制下,ssr1114编码序列置于PBAD启动子控制下,slr0664诱导表达产物对细胞具有毒性作用,ssr1114诱导表达产物具有抗slr0664表达产物的毒性作用。提示slr0664为毒素基因,ssr1114为抗毒素基因,二者组成一个TA系统,但其有关特性和功能尚待进一步证明。
Chromosomally encoded toxin-antitoxin （TA） systems are thought to result in growth arrest and eventual cell death upon exposure to environmental stress in E. coli. In the chromosome of cyanobacteria Synechocystis sp. PCC6803, the genetic organization of a 360 bp open reading frame （ORF）, slr0664, and another small ORF of 256 bp, ssrlll4, is similar to that of TA system. The predicted protein encoded by slr0664 is homologous to RelE, but neither homologue of ssrlll4 nor ssrlll4-encoding protein was found in TA system. To see whether slr0664 encodes a toxin protein, ssrlll4 encodes an antitoxin, an expressing plasmid containing promoter Plac and PBAD, was constructed. In this construct, Both slr0664 and ssrlll4 were controlled by Plac and PBAD, respectively. Expression of slr0664 in Escherichia coli results in the inhi- bition of bacterial growth, the expression of ssrlll4 neutralize the toxicity of slr0664 expression. These resuits show that slr0664 is toxin gene and ssrlll4 is antitoxin gene, both ssrlll4 and slr0664 constitute a chromosomal TA system in Synechocystis sp. PCC6803.
出处
《微生物学通报》
CAS
CSCD
北大核心
2009年第1期31-36,共6页
Microbiology China
基金
国家自然科学基金项目(No.30771176)
江苏大学高级人才专项(No.1283000072)资助
