Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China; School of Communication & Information Engineering, Shanghai University, Shanghai 200444, China.
Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China.
Microbiol Res. 2017 May;198:1-7. doi: 10.1016/j.micres.2017.01.005. Epub 2017 Jan 21.
The two-component system ActS/ActR plays important roles in bacterial adaptation to abiotic stress, including acid tolerance and oxidant resistance. However, the underlying regulatory mechanism is not clear. In this study, we found that the ActS/ActR system is required for adaptation to oxidative stress by regulating the transcription of the genes actR, katB, gshA and gshB1. The actS and actR mutants were sensitive to low pH and oxidants such as HO, oxidized glutathione (GSSG) and sodium nitroprusside (SNP). The expression of actR by using a plasmid rescued the defect of SNP sensitivity for all actS and actR mutants. The expression of actS and actR were suppressed by treatment with HO. The expression of actS, actR, oxyR, katA and katB was required for ActS and ActR under normal conditions. The induction of katB, gshA and gshB1 depended on ActS and ActR during treatment with HO and SNP. Our findings revealed that the ActS/ActR system is a key redox regulator in S. meliltoi and provides a new cue to understanding Rhizobium-legume symbiosis.
双组分系统 ActS/ActR 在细菌适应非生物胁迫方面发挥着重要作用，包括耐酸和抗氧化。然而，其潜在的调控机制尚不清楚。在本研究中，我们发现 ActS/ActR 系统通过调节 actR、katB、gshA 和 gshB1 基因的转录来适应氧化应激。actS 和 actR 突变体对低 pH 和氧化剂如 HO、氧化型谷胱甘肽 (GSSG) 和亚硝戊二烯 (SNP) 敏感。通过质粒表达 actR 挽救了所有 actS 和 actR 突变体对 SNP 敏感性的缺陷。HO 处理抑制了 actS 和 actR 的表达。在正常条件下，actS 和 actR 的表达受到 oxyR、katA 和 katB 的抑制。在处理 HO 和 SNP 时，actS、actR、oxyR、katA 和 katB 的表达是 ActS 和 ActR 所必需的。katB、gshA 和 gshB1 的诱导依赖于 HO 和 SNP 处理时的 ActS 和 ActR。我们的研究结果表明，ActS/ActR 系统是 S. meliloti 中的一个关键氧化还原调节剂，为理解根瘤菌-豆科植物共生关系提供了新的线索。
