The Significance of Type II and PrxQ Peroxiredoxins for Antioxidative Stress Response in the Purple Bacterium Rhodobacter sphaeroides*
The Significance of Type II and PrxQ Peroxiredoxins for Antioxidative Stress Response in the Purple Bacterium Rhodobacter sphaeroides*
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DOI：
10.1074/jbc.m702855200
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发表时间：
2007-09
影响因子：
4.8
通讯作者：
Masahiro Wakita;S. Masuda;K. Motohashi;T. Hisabori;H. Ohta;K. Takamiya
中科院分区：
文献类型：
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作者：
Masahiro Wakita;S. Masuda;K. Motohashi;T. Hisabori;H. Ohta;K. Takamiya
两种过氧化物酶，分类为II型和PrxQ，其特征在于在紫色非硫光合细菌Rhodobacter sphaeroides。两种重组蛋白在体外均表现出显著的硫氧还蛋白依赖性过氧化物酶活性，具有广泛的底物特异性。然而，R.与迄今为止研究的典型PrxQs不同，sphaeroides不包含两个保守的催化Cys残基之一。我们发现R。sphaeroides PrxQ和其他PrxQ样蛋白从几个生物体保存不同的第二个半胱氨酸残基，表明这些蛋白质应归类为一个新的PrxQ亚家族。破坏R.当细胞在需氧光或通过向培养基中外源添加活性氧物质而产生的氧化应激条件下生长时，类球形菌对细胞活力具有显著影响。突变体的生长速率显着下降，与野生型相比，在有氧条件下，但不是厌氧条件下。这些结果表明，过氧化物酶是至关重要的抗氧化应激反应，在这种细菌。基因破坏剂也表现出降低的色素合成水平，表明过氧化物酶直接或间接参与光合机构的合成调节。
Two peroxiredoxins, classified as Type II and PrxQ, were characterized in the purple non-sulfur photosynthetic bacterium Rhodobacter sphaeroides. Both recombinant proteins showed remarkable thioredoxin-dependent peroxidase activity with broad substrate specificity in vitro. Nevertheless, PrxQ of R. sphaeroides, unlike typical PrxQs studied to date, does not contain one of the two conserved catalytic Cys residues. We found that R. sphaeroides PrxQ and other PrxQ-like proteins from several organisms conserve a different second Cys residue, indicating that these proteins should be categorized into a novel PrxQ subfamily. Disruption of either the Type II or PrxQ gene in R. sphaeroides had a dramatic effect on cell viability when the cells were grown under aerobic light or oxidative stress conditions created by exogenous addition of reactive oxygen species to the medium. Growth rates of the mutants were significantly decreased compared with that of wild type under aerobic but not anaerobic conditions. These results indicate that the peroxiredoxins are crucial for antioxidative stress response in this bacterium. The gene disruptants also demonstrated reduced levels of photopigment synthesis, suggesting that the peroxiredoxins are directly or indirectly involved in regulated synthesis of the photosynthetic apparatus.