Oxidative stress tolerance is manganese (Mn2+) regulated in Streptococcus gordonii
Oxidative stress tolerance is manganese (Mn2+) regulated in Streptococcus gordonii
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DOI：
10.1099/00221287-148-10-3255
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发表时间：
2002-10-01
期刊：
影响因子：
2.8
通讯作者：
Jenkinson, HF
中科院分区：
文献类型：
--
作者：
Jakubovics, NS;Smith, AW;Jenkinson, HF
口腔细菌戈登链球菌中的Sca通透酶是锰（Mn 2+）和相关阳离子的ATP结合盒（ABC）型转运蛋白家族的成员，所述锰和相关阳离子在许多感染模型中与链球菌毒力相关。由于Mn 2+在多种细菌中具有抗氧化损伤的保护功能，我们研究了Sca通透酶在格氏链球菌氧化应激耐受中的作用。由sodA编码的单一Mn 2+依赖性超氧化物歧化酶（SOD）由S.并且在氧化应激条件下上调>10倍。sodA的失活导致S. gordonii细胞对氧（O-2）的生长抑制、百草枯（一种超氧阴离子产生剂）和过氧化氢（H2 O2）的杀伤作用。巯基过氧化物酶的表达，由tpx基因直接位于下游的scaCBA操纵子，也上调氧化条件下。tpx的失活导致细胞对H2 O2的敏感性增加，但不对O-2或百草枯。在低Mn ~（2+）培养基（0.01 μ M Mn ~（2+））中，sodA和tpx基因转录下调，SOD活性降低，细胞对O ~（2-）的生长抑制更敏感。Sca permease-deficient（scaC）突变体在含有
The Sca permease in the oral bacterium Streptococcus gordonii is a member of a family of ATP-binding cassette (ABC)-type transporters for manganese (Mn2+) and related cations that are associated with streptococcal virulence in a number of infection models. Since Mn2+ has a protective function against oxidative damage in a variety of bacteria, we have investigated the role of Sca permease in oxidative stress tolerance in Streptococcus gordonii. A single Mn2+-dependent superoxide dismutase (SOD), encoded by sodA, is expressed by S. gordonii and was >10-fold up-regulated under oxidative stress conditions. Inactivation of sodA resulted in increased susceptibility of S. gordonii cells to growth inhibition by dioxygen (O-2), and to killing by paraquat (a superoxide anion generator) and by hydrogen peroxide (H2O2). Expression of thiol peroxidase, encoded by the tpx gene located immediately downstream of the scaCBA operon, was also up-regulated under oxidative conditions. Inactivation of tpx led to increased susceptibility of cells to H2O2, but not to O-2 or paraquat. In low-Mn2+ medium (0.01 muM Mn2+) sodA and tpx genes were transcriptionally down-regulated, SOD activity was reduced and cells were more sensitive to growth inhibition by O-2. A Sca permease-deficient (scaC) mutant showed further reduced SOD activity and hypersensitivity to O-2 in medium containing