CLARiTY 17用于“第2组西格玛因子是蓝藻中氧化应激驯化的中心调节剂”研究
Group 2 Sigma Factors Are Central Regulators of Oxidative Stress Acclimation in Cyanobacteria
当聚集体蓝藻（Synechocystis sp。）时，RNA聚合酶（RNAP）的调节因子根据环境因素调节基因表达。 PCC 6803适应次优条件。在这里，我们显示非必要组2σ因子在氧化应激反应中的核心作用。缺失所有组2σ因子的细胞不能适应化学诱导的单线态氧，超氧化物或H2O2应力并且在高光下失去色素。 SigB和SigD是氧化应激中的主要σ因子，而SigC和SigE仅起次要作用。 SigD因子在高光，单线态氧和H2O2应激中上调，并且ΔsigBCE株中SigD因子的过量产生导致ΔsigBCE细胞在那些应激条件下的优异生长。超氧化物不会诱导SigD因子的产生，而是适度诱导SigB和SigC因子。单独在ΔsigCDE中的SigB因子可以支持几乎与对照菌株中的σ因子的完全补体一样快的超氧化物应激生长，但过量的固定相相关的SigC因子导致ΔsigBDE在超氧化物应激中生长停滞。功能性RNA聚合酶的急剧减少限制了细胞在H2O2应激中的转录能力，这解释了为什么蓝细菌对H2O2敏感。 RNAP-SigB和RNAP-SigD全酶的形成在H2O2应激中高度增强，仅含有SigB（ΔsigCDE）或SigD（ΔsigBCE）的细胞在H2O2应激中显示出优异的生长。
Regulatory σ factors of the RNA polymerase (RNAP) adjust gene expression according to environmental cues when the cyanobacterium Synechocystis sp. PCC 6803 acclimates to suboptimal conditions. Here we show central roles of the non-essential group 2 σ factors in oxidative stress responses. Cells missing all group 2 σ factors fail to acclimate to chemically induced singlet oxygen, superoxide or H2O2 stresses and lose pigments in high light. The SigB and SigD are the major σ factors in oxidative stress whereas SigC and SigE play only minor roles. The SigD factor is upregulated in high light, singlet oxygen and H2O2 stresses, and overproduction of the SigD factor in the ΔsigBCE strain leads to superior growth of ΔsigBCE cells in those stress conditions. Superoxide does not induce the production of the SigD factor but instead SigB and SigC factors are moderately induced. The SigB factor alone in ΔsigCDE can support almost as fast growth in superoxide stress as full complement of σ factors in the control strain but an overdose of the stationary-phase-related SigC factor causes growth arrest of ΔsigBDE in superoxide stress. Drastic decrease of the functional RNA polymerase limits the transcription capacity of the cells in H2O2 stress, which explains why cyanobacteria are sensitive to H2O2. Formation of RNAP-SigB and RNAP-SigD holoenzymes is highly enhanced in H2O2 stress and cells containing only SigB (ΔsigCDE) or SigD (ΔsigBCE) show superior growth in H2O2 stress.
https://academic.oup.com/pcp/advance-article/doi/10.1093/pcp/pcy221/5165573
