Distinct Characteristics of Two 2-Cys Peroxiredoxins of Vibrio vulnificus Suggesting Differential Roles in Detoxifying Oxidative Stress
Distinct Characteristics of Two 2-Cys Peroxiredoxins of Vibrio vulnificus Suggesting Differential Roles in Detoxifying Oxidative Stress
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DOI：
10.1074/jbc.m112.421214
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发表时间：
2012-12-14
影响因子：
4.8
通讯作者：
Choi, Sang Ho
中科院分区：
文献类型：
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作者：
Bang, Ye-Ji;Oh, Man Hwan;Choi, Sang Ho
过氧化还原蛋白 (Prxs) 是普遍存在的抗氧化酶，可减少有毒过氧化物。在兼性需氧病原体创伤弧菌中鉴定出两种不同的 2-Cys Prx，Prx1 和 Prx2。两个 Prx 都有两个保守的催化半胱氨酸，C-P 和 C-R，但 Prx2 在氨基酸序列上与真核 Prx 的同源性高于与 Prx1 的同源性。 Prx2 使用硫氧还蛋白 A 作为还原剂，而 Prx1 需要 AhpF。 Prx2 含有与敏感 Prx 中保守的基序相似的 GGIG 和 FL 基序，并表现出对过度氧化的敏感性。 MS分析和C-P-SO3H特异性免疫印迹证明C-P在体外和体内分别过度氧化为C-P-SO2H（或C-P-SO3H）。相比之下，Prx1 很稳健，并且 C-P 没有过度氧化。 Prxs 的离散表达表明 Prx2 是由微量的 H2O2 诱导的，因此驻留在有氧生长的细胞中。相反，Prx1 有时仅在暴露于高水平 H2O2 的细胞中表达。诱变研究表明，缺乏 Prx2 会积累足够的 H2O2 来诱导 Prx1。动力学特性表明，Prx2 由于其与 H2O2 的高亲和力而有效清除低水平的过氧化物，而 Prx1 由于其高周转率和更有效的再激活而快速降解较高水平的过氧化物。这项研究表明，两种 Prx 在解毒不同范围的 H2O2 方面进行了差异优化，并提出 Prx2 是内源产生的过氧化物的住宅清除剂，而 Prx1 是外源遇到的过氧化物的偶尔清除剂。此外，基因组序列数据库搜索预测这两种 Prx 在细菌中广泛共存。
Peroxiredoxins (Prxs) are ubiquitous antioxidant enzymes reducing toxic peroxides. Two distinct 2-Cys Prxs, Prx1 and Prx2, were identified in Vibrio vulnificus, a facultative aerobic pathogen. Both Prxs have two conserved catalytic cysteines, C-P and C-R, but Prx2 is more homologous in amino acid sequences to eukaryotic Prx than to Prx1. Prx2 utilized thioredoxin A as a reductant, whereas Prx1 required AhpF. Prx2 contained GGIG and FL motifs similar to the motifs conserved in sensitive Prxs and exhibited sensitivity to overoxidation. MS analysis and C-P-SO3H specific immunoblotting demonstrated overoxidation of C-P to C-P-SO2H (or C-P-SO3H) in vitro and in vivo, respectively. In contrast, Prx1 was robust and C-P was not overoxidized. Discrete expression of the Prxs implied that Prx2 is induced by trace amounts of H2O2 and thereby residential in cells grown aerobically. In contrast, Prx1 was occasionally expressed only in cells exposed to high levels of H2O2. A mutagenesis study indicated that lack of Prx2 accumulated sufficient H2O2 to induce Prx1. Kinetic properties indicated that Prx2 effectively scavenges low levels of peroxides because of its high affinity to H2O2, whereas Prx1 quickly degrades higher levels of peroxides because of its high turnover rate and more efficient reactivation. This study revealed that the two Prxs are differentially optimized for detoxifying distinct ranges of H2O2, and proposed that Prx2 is a residential scavenger of peroxides endogenously generated, whereas Prx1 is an occasional scavenger of peroxides exogenously encountered. Furthermore, genome sequence database search predicted widespread coexistence of the two Prxs among bacteria.