Sánchez-Riego Ana M, Mata-Cabana Alejandro, Galmozzi Carla V, Florencio Francisco J
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas Seville, Spain.
Front Microbiol. 2016 Aug 18;7:1283. doi: 10.3389/fmicb.2016.01283. eCollection 2016.
NADPH-thioredoxin reductase C (NTRC) is a bimodular enzyme composed of an NADPH-thioredoxin reductase and a thiioredoxin domain extension in the same protein. In plants, NTRC has been described to be involved in the protection of the chloroplast against oxidative stress damage through reduction of the 2-Cys peroxiredoxin (2-Cys Prx) as well as through other functions related to redox enzyme regulation. In cyanobacteria, the Anabaena NTRC has been characterized in vitro, however, nothing was known about its in vivo function. In order to study that, we have generated the first knockout mutant strain (ΔntrC), apart from the previously described in Arabidopsis. Detailed characterization of this strain reveals a differential sensitivity to oxidative stress treatments with respect to the wild-type Anabaena strain, including a higher level of ROS (reactive oxygen species) in normal growth conditions. In the mutant strain, different oxidative stress treatments such as hydrogen peroxide, methyl-viologen or high light irradiance provoke an increase in the expression of genes related to ROS detoxification, including AnNTRC and peroxiredoxin genes, with a concomitant increase in the amount of AnNTRC and 2-Cys Prx. Moreover, the role of AnNTRC in the antioxidant response is confirmed by the observation of a pronounced overoxidation of the 2-Cys Prx and a time-delay recovery of the reduced form of this protein upon oxidative stress treatments. Our results suggest the participation of this enzyme in the peroxide detoxification in Anabaena. In addition, we describe the role of Anabaena NTRC in thermotolerance, by the appearance of high molecular mass AnNTRC complexes, showing that the mutant strain is more sensitive to high temperature treatments.
NADPH-硫氧还蛋白还原酶C（NTRC）是一种双模块酶，由同一个蛋白质中的NADPH-硫氧还蛋白还原酶和硫氧还蛋白结构域延伸组成。在植物中，NTRC已被描述为通过还原2-半胱氨酸过氧化物酶（2-Cys Prx）以及通过与氧化还原酶调节相关的其他功能，参与保护叶绿体免受氧化应激损伤。在蓝细菌中，鱼腥藻NTRC已在体外进行了表征，然而，对其体内功能却一无所知。为了研究这一点，除了先前在拟南芥中描述的之外，我们构建了第一个基因敲除突变株（ΔntrC）。对该菌株的详细表征揭示了其对氧化应激处理的敏感性与野生型鱼腥藻菌株不同，包括在正常生长条件下具有更高水平的活性氧（ROS）。在突变株中，不同的氧化应激处理，如过氧化氢、甲基紫精或高光辐照，会导致与ROS解毒相关的基因表达增加，包括AnNTRC和过氧化物酶基因，同时AnNTRC和2-Cys Prx的量也会增加。此外，通过观察到2-Cys Prx明显过度氧化以及在氧化应激处理后该蛋白还原形式的延迟恢复，证实了AnNTRC在抗氧化反应中的作用。我们的结果表明该酶参与了鱼腥藻中的过氧化物解毒。此外，我们描述了鱼腥藻NTRC在耐热性中的作用，通过高分子量AnNTRC复合物的出现表明突变株对高温处理更敏感。
