Paulo Esther, García-Santamarina Sarela, Calvo Isabel A, Carmona Mercè, Boronat Susanna, Domènech Alba, Ayté José, Hidalgo Elena
Oxidative Stress and Cell Cycle Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/ Dr. Aiguader 88, E-08003, Barcelona, Spain.
Mol Microbiol. 2014 Apr;92(2):246-57. doi: 10.1111/mmi.12548. Epub 2014 Mar 6.
The main peroxiredoxin in Schizosaccharomyces pombe, Tpx1, is important to sustain aerobic growth, and cells lacking this protein are only able to grow on solid plates under anaerobic conditions. We have found that deletion of the gene coding for thioredoxin reductase, trr1, is a suppressor of the sensitivity to aerobic growth of Δtpx1 cells, so that cells lacking both proteins are able to grow on solid plates in the presence of oxygen. We have investigated this suppression effect, and determined that it depends on the presence of catalase, which is constitutively expressed in Δtrr1 cells in a transcription factor Pap1-dependent manner. A complete characterization of the repertoire of hydrogen peroxide scavenging activities in fission yeast suggests that Tpx1 is the only enzyme with sufficient sensitivity for peroxides and cellular abundance as to control the low levels produced during aerobic growth, catalase being the next barrier of detoxification when the steady-state levels of peroxides are increased in Δtpx1 cells. Gpx1, the only glutathione peroxidase encoded by the S. pombe genome, only has a minor secondary role when extracellular peroxides are added. Our study proposes non-overlapping roles for the different hydrogen peroxide scavenging activities of this eukaryotic organism.
粟酒裂殖酵母中的主要过氧化物还原酶Tpx1对维持有氧生长很重要，缺乏该蛋白的细胞仅能在厌氧条件下在固体平板上生长。我们发现，编码硫氧还蛋白还原酶的基因trr1的缺失是Δtpx1细胞对有氧生长敏感性的一种抑制因素，因此缺乏这两种蛋白的细胞能够在有氧条件下在固体平板上生长。我们研究了这种抑制作用，并确定其依赖于过氧化氢酶的存在，过氧化氢酶在Δtrr1细胞中以转录因子Pap1依赖的方式组成性表达。对裂殖酵母中过氧化氢清除活性库的完整表征表明，Tpx1是唯一对过氧化物具有足够敏感性且细胞丰度足以控制有氧生长过程中产生的低水平过氧化物的酶，当Δtpx1细胞中过氧化物的稳态水平升高时，过氧化氢酶是下一道解毒屏障。粟酒裂殖酵母基因组编码的唯一谷胱甘肽过氧化物酶Gpx1，在添加细胞外过氧化物时仅起次要的辅助作用。我们的研究提出了这种真核生物不同过氧化氢清除活性的非重叠作用。
