Protection of Xanthomonas against arsenic toxicity involves the peroxide-sensing transcription regulator OxyR
Protection of Xanthomonas against arsenic toxicity involves the peroxide-sensing transcription regulator OxyR
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DOI：
10.1016/j.resmic.2004.07.005
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发表时间：
2005-01-01
影响因子：
2.6
通讯作者：
Mongkolsuk, S
中科院分区：
文献类型：
--
作者：
Sukchawalit, R;Prapagdee, B;Mongkolsuk, S
砷已被证明通过诱导产生活性氧来介导其毒性。在这里，我们研究了氧化胁迫诱导基因（katA，ahpC和ohr）和它们的调节器（oxyR和ohrR）在响应砷处理的植物病原细菌，野油菜黄单胞菌pv。菜豆（Phaseoli）（Xp.）过量生产的过氧化物清除酶（KatA，AhpCF和Ohr）并没有提高野生型XP的砷耐受性。此外，katA，ahpC，ohr和ohrR基因的失活对砷抗性水平没有影响。相比之下，oxyR突变体（Xp oxyR）表现出增加的敏感性，五价砷酸盐，并在更大程度上，三价亚砷酸盐。细胞对亚砷酸盐处理的抵抗力受铁水平的显著影响。在过量铁的存在下，细胞对亚砷酸盐杀伤的敏感性增加10倍，而通过铁螯合剂（2.2 '-联吡啶）去除铁保护黄单胞菌免受亚砷酸盐毒性。亚砷酸盐敏感表型的Xp oxyR可以补充的功能OxyR从质粒载体的表达，但不是由其他已知的OxyR调节的过氧化物清除酶，如KatA和AhpCF，Ohr和OhrR的表达。这些数据表明，尚未鉴定的OxyR调控基因参与赋予Xp的砷抗性。据我们所知，这是第一份报告表明，过氧化物敏感调节剂OxyR参与抗砷。(C)2004年，Elsevier SAS。All rights reserved.
Arsenic has been shown to mediate its toxicity through induced generation of reactive oxygen species. Here, we examined the role of oxidative stress-inducible genes (katA, ahpC and ohr) and their regulators (oxyR and ohrR) in the response to arsenic treatment in a plant pathogenic bacterium, Xanthomonas campestris pv. phaseoli (Xp). Overproduction of peroxide-scavenging enzymes (KatA, AhpCF and Ohr) did not enhance arsenic tolerance in wild-type Xp. Furthermore, inactivation of katA, ahpC, ohr, and ohrR genes had no effect on the level of arsenic resistance. By contrast, an oxyR mutant (Xp oxyR) showed increased sensitivity to both pentavalent arsenate and, to a greater extent, trivalent arsenite. The resistance of cells to arsenite treatment was significantly affected by the level of iron. Cells were 10-fold more sensitive to arsenite killing in the presence of excess iron, while removal of iron by an iron chelator (2.2'-dipyridyl) protected Xanthomonas from arsenite toxicity. The arsenite-sensitive phenotype of Xp oxyR could be complemented by the expression of functional OxyR from a plasmid vector, but not by the expression of other known OxyR-regulated peroxide-scavenging enzymes such as KatA and AhpCF, Ohr and OhrR. The data suggested that as yet unidentified, OxyR-regulated gene(s) are involved in conferring arsenic resistance in Xp. To our knowledge, this is the first report showing that the peroxide-sensing regulator OxyR is involved in arsenic resistance. (C) 2004 Elsevier SAS. All rights reserved.