State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, P.R. China.
W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA.
J Microbiol Biotechnol. 2023 Mar 28;33(3):299-309. doi: 10.4014/jmb.2209.09006. Epub 2023 Jan 20.
Glutathione peroxidases (Gpx) are a group of antioxidant enzymes that protect cells or tissues against damage from reactive oxygen species (ROS). The Gpx proteins identified in mammals exhibit high catalytic activity toward glutathione (GSH). In contrast, a variety of non-mammalian Gpx proteins from diverse organisms, including fungi, plants, insects, and rodent parasites, show specificity for thioredoxin (TRX) rather than GSH and are designated as TRX-dependent peroxiredoxins. However, the study of the properties of Gpx in the environmental microbiome or isolated bacteria is limited. In this study, we analyzed the Gpx sequences, identified the characteristics of sequences and structures, and found that the environmental microbiome Gpx proteins should be classified as TRX-dependent, Gpx-like peroxiredoxins. This classification is based on the following three items of evidence: i) the conservation of the peroxidatic Cys residue; ii) the existence and conservation of the resolving Cys residue that forms the disulfide bond with the peroxidatic cysteine; and iii) the absence of dimeric and tetrameric interface domains. The conservation/divergence pattern of all known bacterial Gpx-like proteins in public databases shows that they share common characteristics with that from the environmental microbiome and are also TRX-dependent. Moreover, phylogenetic analysis shows that the bacterial Gpx-like proteins exhibit a star-like radiating phylogenetic structure forming a highly diverse genetic pool of TRX-dependent, Gpx-like peroxidases.
谷胱甘肽过氧化物酶（Gpx）是一组抗氧化酶，可保护细胞或组织免受活性氧（ROS）的损伤。哺乳动物中鉴定的 Gpx 蛋白对谷胱甘肽（GSH）表现出高催化活性。相比之下，来自真菌、植物、昆虫和啮齿动物寄生虫等多种生物体的各种非哺乳动物 Gpx 蛋白对硫氧还蛋白（TRX）而不是 GSH 具有特异性，并被指定为 TRX 依赖性过氧化物酶。然而，对环境微生物组或分离细菌中的 Gpx 特性的研究是有限的。在这项研究中，我们分析了 Gpx 序列，确定了序列和结构的特征，并发现环境微生物组 Gpx 蛋白应归类为 TRX 依赖性、Gpx 样过氧化物酶。这种分类基于以下三个证据：i）过氧物酶 Cys 残基的保守性；ii）与过氧物酶半胱氨酸形成二硫键的解析 Cys 残基的存在和保守性；iii）无二聚体和四聚体界面结构域。所有已知细菌 Gpx 样蛋白在公共数据库中的保守/分歧模式表明，它们与环境微生物组具有共同特征，并且也是 TRX 依赖性的。此外，系统发育分析表明，细菌 Gpx 样蛋白表现出星状放射状系统发育结构，形成了 TRX 依赖性、Gpx 样过氧化物酶的高度多样化遗传库。
