Regulation of the Intracellular Free Iron Pool by Dpr Provides Oxygen Tolerance to Streptococcus mutans
Regulation of the Intracellular Free Iron Pool by Dpr Provides Oxygen Tolerance to Streptococcus mutans
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DOI：
10.1128/jb.186.18.5997-6002.2004
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发表时间：
2004-09
影响因子：
3.2
通讯作者：
Yuji Yamamoto;K. Fukui;Naoko Koujin;H. Ohya;K. Kimura;Y. Kamio
中科院分区：
文献类型：
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作者：
Yuji Yamamoto;K. Fukui;Naoko Koujin;H. Ohya;K. Kimura;Y. Kamio
摘要DPR是变形链球菌耐氧所必需的铁结合蛋白。我们先前提出，DPR可以通过隔离细胞内的游离铁离子来催化产生剧毒的自由基(Y.Yamamoto，M.Higuchi，L.B.Poole和Y.Kamio，J.细菌素)，从而增强细菌的耐氧性。182：3740-3747,2000；Y.Y.Yamamoto，L.B.Poole，R.R.Hantgan，和Y.Kamio，J.细菌素。184：2931-2939,2002)。在这里，我们用电子自旋共振光谱仪检测了暴露于空气前后的野生型(WT)和DPR突变株的细胞内游离铁状态。在厌氧条件下，WT和DPR菌株的游离铁离子浓度分别为225.9±2.6和333.0±61.3μM。WT细胞暴露于空气1h后，细胞内游离铁离子浓度降至(2 2.5±5.3)μM，细胞内铁离子浓度维持在(230.3±2 8.8)μM。这些数据表明，DPR对细胞内游离铁库的调节是变形链球菌耐氧性所必需的。
ABSTRACT Dpr is an iron-binding protein required for oxygen tolerance in Streptococcus mutans. We previously proposed that Dpr could confer oxygen tolerance to the bacterium by sequestering intracellular free iron ions that catalyze generation of highly toxic radicals (Y. Yamamoto, M. Higuchi, L. B. Poole, and Y. Kamio, J. Bacteriol. 182:3740-3747, 2000; Y. Yamamoto, L. B. Poole, R. R. Hantgan, and Y. Kamio, J. Bacteriol. 184:2931-2939, 2002). Here, we examined the intracellular free iron status of wild-type (WT) and dpr mutant strains of S. mutans, before and after exposure to air, by using electron spin resonance spectrometry. Under anaerobic conditions, free iron ion concentrations of WT and dpr strains were 225.9 ± 2.6 and 333.0 ± 61.3 μM, respectively. Exposure of WT cells to air for 1 h induced Dpr expression and reduced intracellular free iron ion concentrations to 22.5 ± 5.3 μM; under these conditions, dpr mutant cells maintained intracellular iron concentration at 230.3 ± 28.8 μM. A decrease in cell viability and genomic DNA degradation was observed in the dpr mutant exposed to air. These data indicate that regulation of the intracellular free iron pool by Dpr is required for oxygen tolerance in S. mutans.