Liu Daixi, Song Hui, Li Yuanning, Huang Ranran, Liu Hongyue, Tang Kunxian, Jiao Nianzhi, Liu Jihua
Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China.
School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China.
Antioxidants (Basel). 2023 Feb 9;12(2):423. doi: 10.3390/antiox12020423.
Cyanobacteria can perform both anoxygenic and oxygenic photosynthesis, a characteristic which ensured that these organisms were crucial in the evolution of the early Earth and the biosphere. Reactive oxygen species (ROS) produced in oxygenic photosynthesis and reactive sulfur species (RSS) produced in anoxygenic photosynthesis are closely related to intracellular redox equilibrium. ROS comprise superoxide anion (O), hydrogen peroxide (HO), and hydroxyl radicals (OH). RSS comprise HS and sulfane sulfur (persulfide, polysulfide, and S). Although the sensing mechanism for ROS in cyanobacteria has been explored, that of RSS has not been elucidated. Here, we studied the function of the transcriptional repressor PerR in RSS sensing in sp. PCC7002 (PCC7002). PerR was previously reported to sense ROS; however, our results revealed that it also participated in RSS sensing. PerR repressed the expression of and downregulated the tolerance of PCC7002 to polysulfide (HS). The reporter system indicated that PerR sensed HS. Cys of the Cys4:Zn site, which contains four cysteines (Cys, Cys, Cys, and Cys) bound to one zinc atom, could be modified by HS to Cys-SSH, as a result of which the zinc atom was released from the site. Moreover, Cys could also be modified by polysulfide to Cys-SSH. Thus, our results reveal that PerR, a representative of the Cys zinc finger proteins, senses HS. Our findings provide a new perspective to explore the adaptation strategy of cyanobacteria in Proterozoic and contemporary sulfurization oceans.
蓝藻既能进行不产氧光合作用，也能进行产氧光合作用，这一特性确保了这些生物在早期地球和生物圈的演化中至关重要。产氧光合作用中产生的活性氧（ROS）和不产氧光合作用中产生的活性硫物质（RSS）与细胞内氧化还原平衡密切相关。ROS包括超氧阴离子（O）、过氧化氢（HO）和羟基自由基（OH）。RSS包括HS和硫烷硫（过硫化物、多硫化物和S）。尽管已经对蓝藻中ROS的传感机制进行了探索，但RSS的传感机制尚未阐明。在这里，我们研究了转录阻遏物PerR在sp. PCC7002（PCC7002）中对RSS传感的功能。此前有报道称PerR能感知ROS；然而，我们的结果表明它也参与了RSS传感。PerR抑制了的表达，并下调了PCC7002对多硫化物（HS）的耐受性。报告系统表明PerR能感知HS。Cys4:Zn位点的半胱氨酸（Cys），该位点包含四个与一个锌原子结合的半胱氨酸（Cys、Cys、Cys和Cys），可被HS修饰为Cys-SSH，结果锌原子从该位点释放。此外，Cys也可被多硫化物修饰为Cys-SSH。因此，我们的结果表明，作为半胱氨酸锌指蛋白的代表，PerR能感知HS。我们的发现为探索蓝藻在元古代和当代硫化海洋中的适应策略提供了新的视角。
