MULTICELLULAR OXIDANT DEFENSE IN UNICELLULAR ORGANISMS
MULTICELLULAR OXIDANT DEFENSE IN UNICELLULAR ORGANISMS
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DOI：
10.1073/pnas.89.17.7924
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发表时间：
1992-09-01
影响因子：
11.1
通讯作者：
EATON, JW
中科院分区：
文献类型：
--
作者：
MA, M;EATON, JW
虽然过氧化氢酶被认为是对过氧化氢（H2 O2）的主要防御，但单个大肠杆菌内的过氧化氢酶活性不能保护免受外源H2 O2的侵害。与先前的报道相反，我们发现野生型和过氧化氢酶缺陷型大肠杆菌的稀释悬浮液。大肠杆菌对H2 O2的敏感性是相同的，这可能是因为即使是野生型的过氧化氢酶阳性的大肠杆菌。大肠杆菌不能维持这种高扩散性氧化剂的内部/外部浓度梯度。然而，过氧化氢酶阳性E.大肠杆菌优先存活H2 O2挑战，甚至可以交叉保护相邻的过氧化氢酶缺乏的生物体。此外，高密度过氧化氢酶阳性而非过氧化氢酶阴性的E。大肠杆菌可以在竞争性的、产生过氧化物的链球菌的存在下存活和繁殖。这些观察结果支持了细菌过氧化氢酶可能保护菌落而不是个体的概念。大肠杆菌对环境H2 O2的抗性。通过减轻氧化应激的酶的活性进行的群体保护可能是多细胞生物进化的驱动力。
Although catalase is thought to be a major defense against hydrogen peroxide (H2O2), the catalase activity within individual Escherichia coli fails to protect against exogenous H2O2. Contrary to earlier reports, we find that dilute suspensions of wild-type and catalase-deficient E. coli are identical in their sensitivity to H2O2, perhaps because even wild-type, catalase-positive E. coli cannot maintain an internal/external concentration gradient of this highly diffusible oxidant. However, concentrated suspensions or colonies of catalase-positive E. coli do preferentially survive H2O2 challenge and can even cross-protect adjacent catalase-deficient organisms. Furthermore, high-density catalase-positive but not catalase-negative-E. coli can survive and multiply in the presence of competitive, peroxide-generating streptococci. These observations support the concept that bacterial catalase may defend colonial, but not individual, E. coli against environmental H2O2. Group protection by the activity of enzymes that mitigate oxidative stress may have been a driving force in the evolution of multicellular organisms.