The Entner-Doudoroff pathway empowers Pseudomonas putida KT2440 with a high tolerance to oxidative stress
The Entner-Doudoroff pathway empowers Pseudomonas putida KT2440 with a high tolerance to oxidative stress
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DOI：
10.1111/1462-2920.12069
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发表时间：
2013-06-01
影响因子：
5.1
通讯作者：
Lorenzo, Victor
中科院分区：
文献类型：
--
作者：
Chavarria, Max;Nikel, Pablo I.;Lorenzo, Victor
恶臭假单胞菌的葡萄糖代谢由于缺乏6-磷酸果糖激酶而仅通过Entner-Doudoroff（艾德）途径进行。为了激活Embden-Meyerhof-Parnas（EMP）途径，我们将pfkA基因从大肠杆菌转移到恶臭假单胞菌野生型菌株以及eda突变体，即缺乏2-酮-3-脱氧-6-磷酸葡萄糖酸醛缩酶。PfkAE.coli未能将碳流从艾德途径重定向到EMP途径，表明艾德对糖催化剂是必需的。PfkAE.coli的存在对生长有害，这可以追溯到ATP和NAD（P）H池的减少沿着NAD（P）H/NADP+比率的改变。携带PfkAE.coli的恶臭假单胞菌细胞变得对二酰胺和过氧化氢高度敏感，对它们的反应非常需要NADPH。甲硫氨酸对PfkAE.coli的抑制作用有一定的抑制作用，其合成依赖于NADPH。这些结果揭示了艾德途径在产生氧化还原货币（NADPH）中的作用，这是对抗氧化应激所必需的。因此，环境细菌更倾向于艾德途径而不是EMP途径，这样做是为了调整它们的有氧代谢以耐受氧化相关的损伤。
Glucose catabolism of Pseudomonas putida is carried out exclusively through the Entner-Doudoroff (ED) pathway due to the absence of 6-phosphofructokinase. In order to activate the Embden-Meyerhof-Parnas (EMP) route we transferred the pfkA gene from Escherichia coli to a P.putida wild-type strain as well as to an eda mutant, i.e. lacking 2-keto-3-deoxy-6-phosphogluconate aldolase. PfkAE.coli failed to redirect the carbon flow from the ED route towards the EMP pathway, suggesting that ED was essential for sugar catabolism. The presence of PfkAE.coli was detrimental for growth, which could be traced to the reduction of ATP and NAD(P)H pools along with alteration of the NAD(P)H/NADP+ ratio. Pseudomonas putida cells carrying PfkAE.coli became highly sensitive to diamide and hydrogen peroxide, the response to which is very demanding of NADPH. The inhibitory effect of PfkAE.coli could in part be relieved by methionine, the synthesis of which relies much on NADPH. These results expose the role of the ED pathway for generating the redox currency (NADPH) that is required for counteracting oxidative stress. It is thus likely that environmental bacteria that favour the ED pathway over the EMP pathway do so in order to gear their aerobic metabolism to endure oxidative-related insults.