CLARiTY 17用于“第2組西格瑪因子是藍藻中氧化應(yīng)激馴化的中心調(diào)節(jié)劑”研究
Group 2 Sigma Factors Are Central Regulators of Oxidative Stress Acclimation in Cyanobacteria
當聚集體藍藻（Synechocystis sp。）時，RNA聚合酶（RNAP）的調(diào)節(jié)因子根據(jù)環(huán)境因素調(diào)節(jié)基因表達。 PCC 6803適應(yīng)次優(yōu)條件。在這里，我們顯示非必要組2σ因子在氧化應(yīng)激反應(yīng)中的核心作用。缺失所有組2σ因子的細胞不能適應(yīng)化學(xué)誘導(dǎo)的單線態(tài)氧，超氧化物或H2O2應(yīng)力并且在高光下失去色素。 SigB和SigD是氧化應(yīng)激中的主要σ因子，而SigC和SigE僅起次要作用。 SigD因子在高光，單線態(tài)氧和H2O2應(yīng)激中上調(diào)，并且ΔsigBCE株中SigD因子的過量產(chǎn)生導(dǎo)致ΔsigBCE細胞在那些應(yīng)激條件下的優(yōu)異生長。超氧化物不會誘導(dǎo)SigD因子的產(chǎn)生，而是適度誘導(dǎo)SigB和SigC因子。單獨在ΔsigCDE中的SigB因子可以支持幾乎與對照菌株中的σ因子的完全補體一樣快的超氧化物應(yīng)激生長，但過量的固定相相關(guān)的SigC因子導(dǎo)致ΔsigBDE在超氧化物應(yīng)激中生長停滯。功能性RNA聚合酶的急劇減少限制了細胞在H2O2應(yīng)激中的轉(zhuǎn)錄能力，這解釋了為什么藍細菌對H2O2敏感。 RNAP-SigB和RNAP-SigD全酶的形成在H2O2應(yīng)激中高度增強，僅含有SigB（ΔsigCDE）或SigD（ΔsigBCE）的細胞在H2O2應(yīng)激中顯示出優(yōu)異的生長。
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
