Liu Enfu, Ye Jiang, Song ShanShan, Wang Keping, Zhang Yuanxing, Zhang Huizhan
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, P. R., China.
J Basic Microbiol. 2014 Jul;54(7):678-87. doi: 10.1002/jobm.201300622. Epub 2014 Mar 14.
Edwardsiella tarda the etiological agent for edwardsiellosis, a devastating fish disease prevailing in worldwide aquaculture industries was subjected to a molecular genetic study. To research into the influence when RpoN (σ(54) ) and RpoS (σ(38) ) were deleted simultaneously, the double deletion mutant of RpoN (σ(54) ) and RpoS (σ(38) ), namely rnrs, was constructed. Firstly, RpoN and RpoS are both essential for H2 O2 , starvation, high osmotic pressure and acid resistance, which have synergistic effect. Secondly, virulence of rnrs reduces significantly compared to E. tarda EIB 202 WT, ΔrpoN mutant and ΔrpoS mutant. Furthermore, transcriptional control of rpoS by rpoN in stationary phase was observed through qRT-PCR, while rpoS had no influence on rpoN in the level of transcription. Meanwhile, regulation of flagellar sigma factor σ(F) (FliA) and other flagella-related genes including flgA, flgK, flgL, motA, and motB by rpoS, and rpoN was found. fliA and other flagella-related genes were controlled positively by rpoN, while negatively by rpoS. At last, two differential expression genes in transcriptional level of rnrs strain were detected by DD-RT-PCR, namely cheY and narK. This study therefore indicated interaction between sigma factors RpoN and RpoS, which modulates stress response, virulence, motility, and provides new insights into the regulatory networks of E. tarda.
迟缓爱德华氏菌是爱德华氏菌病的病原体，这是一种在全球水产养殖业中普遍存在的毁灭性鱼类疾病，对其进行了分子遗传学研究。为了研究RpoN（σ(54) ）和RpoS（σ(38) ）同时缺失时的影响，构建了RpoN（σ(54) ）和RpoS（σ(38) ）的双缺失突变体，即rnrs。首先，RpoN和RpoS对于H2O2、饥饿、高渗透压和耐酸性都是必需的，它们具有协同作用。其次，与迟缓爱德华氏菌EIB 202野生型、ΔrpoN突变体和ΔrpoS突变体相比，rnrs的毒力显著降低。此外，通过qRT-PCR观察到在稳定期rpoN对rpoS的转录调控，而rpoS在转录水平上对rpoN没有影响。同时，发现rpoS和rpoN对鞭毛sigma因子σ(F)（FliA）以及其他鞭毛相关基因（包括flgA、flgK、flgL、motA和motB）有调控作用。fliA和其他鞭毛相关基因受rpoN正调控，受rpoS负调控。最后，通过DD-RT-PCR检测到rnrs菌株转录水平上的两个差异表达基因，即cheY和narK。因此，本研究表明sigma因子RpoN和RpoS之间存在相互作用，这种相互作用调节应激反应、毒力、运动性，并为迟缓爱德华氏菌的调控网络提供了新的见解。
