Jeong Soyoung, Jung Jong-Hyun, Kim Min-Kyu, de Groot Arjan, Blanchard Laurence, Ryu Sangryeol, Bahn Yong-Sun, Lim Sangyong
Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup 56212, Korea.
Department of Food and Animal Biotechnology, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea.
Antioxidants (Basel). 2021 Jul 20;10(7):1148. doi: 10.3390/antiox10071148.
is a robust bacterium with extraordinary resistance to ionizing radiation and reactive oxygen species (ROS). produces an antioxidant thiol compound called bacillithiol (BSH), but BSH-related enzymes have not been investigated. The mutant lacking (_), the first gene of the BSH biosynthetic pathway, was devoid of BSH and sensitive to hydrogen peroxide (HO) compared to the wild-type . strain. Three bacilliredoxin (Brx) proteins, BrxA, B, and C, have been identified in BSH-producing bacteria, such as . . possesses DR_1832, a putative homolog of BrxC. However, because DR_1832 contains a novel signature motif (TCHKT) and a C-terminal region similar to the colicin-like immunity domain, we named it AbxC (atypical BrxC). The deletion of also sensitized cells to HO. AbxC exhibited peroxidase activity in vitro, which was linked to nicotinamide adenine dinucleotide phosphate (NADPH) oxidation via the BSH disulfide reductase DR_2623 (DrBdr). AbxC proteins were present mainly as dimers after exposure to HO in vitro, and the oxidized dimers were resolved to monomers by the reaction coupled with BSH as an electron donor, in which DrBdr transported reducing equivalents from NADPH to AbxC through BSH recycling. We identified 25 proteins that potentially interact with AbxC using AbxC-affinity chromatography. Most of them are associated with cellular metabolisms, such as glycolysis and amino acid biosynthesis, and stress response. Interestingly, AbxC could bind to the proposed peroxide-sensing transcription regulator, DrOxyR. These results suggest that AbxC may be involved in the HO signaling mechanism mediated by DrOxyR.
是一种对电离辐射和活性氧（ROS）具有非凡抗性的顽强细菌。它产生一种名为杆菌硫醇（BSH）的抗氧化硫醇化合物，但与BSH相关的酶尚未得到研究。缺乏BSH生物合成途径第一个基因（_）的突变体，与野生型菌株相比，不含BSH且对过氧化氢（HO）敏感。在产生BSH的细菌中已鉴定出三种杆菌型铁氧还蛋白（Brx），即BrxA、B和C。拥有DR_1832，它是BrxC的假定同源物。然而，由于DR_1832包含一个新的特征基序（TCHKT）和一个类似于大肠杆菌素样免疫结构域的C末端区域，我们将其命名为AbxC（非典型BrxC）。缺失该基因也使细胞对HO敏感。AbxC在体外表现出过氧化物酶活性，这与通过BSH二硫还原酶DR_2623（DrBdr）的烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化有关。在体外暴露于HO后，AbxC蛋白主要以二聚体形式存在，氧化的二聚体通过与作为电子供体的BSH偶联的反应分解为单体，其中DrBdr通过BSH循环将还原当量从NADPH转运到AbxC。我们使用AbxC亲和色谱法鉴定了25种可能与AbxC相互作用的蛋白质。它们中的大多数与细胞代谢相关，如糖酵解和氨基酸生物合成，以及应激反应。有趣的是，AbxC可以与拟议的过氧化物感应转录调节因子DrOxyR结合。这些结果表明，AbxC可能参与由DrOxyR介导的HO信号传导机制。
