Identification of succinate exporter in Corynebacterium glutamicum and its physiological roles under anaerobic conditions
Identification of succinate exporter in Corynebacterium glutamicum and its physiological roles under anaerobic conditions
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DOI：
10.1016/j.jbiotec.2011.03.010
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发表时间：
2011-06-10
影响因子：
4.1
通讯作者：
Abe, Keietsu
中科院分区：
文献类型：
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作者：
Fukui, Keita;Koseki, Chie;Abe, Keietsu
谷氨酸棒杆菌在微需氧和厌氧条件下通过还原三羧酸循环从葡萄糖产生琥珀酸。我们鉴定了谷氨酸棒杆菌的 NCgl2130 基因作为一种新型琥珀酸输出蛋白，在琥珀酸生产中发挥作用，并将其命名为 sucE1。 sucE1在微需氧条件下的表达水平高于有氧条件下的表达水平，并且sucE1的过度表达或破坏分别增加或降低发酵过程中的琥珀酸生产率。在微氧条件下，sucE1 破坏株 sucE1 Delta 的琥珀酸生产率比亲本菌株低 30%，糖消耗率也较低。在厌氧条件下，sucE1 Delta 停止生产琥珀酸。微氧条件下sucE1 Delta细胞内琥珀酸和1,6-二磷酸果糖水平分别比亲本菌株高1.7倍和1.6倍，表明SucE1功能丧失导致琥珀酸无法从细胞中去除，导致细胞内积累，抑制上游糖代谢。同源性和跨膜螺旋搜索鉴定出 SucE1 是属于天冬氨酸：丙氨酸交换器 (AAE) 家族的膜蛋白。部分纯化的 6x-组氨酸标记的 SucE1 (SucE1-[His](6)) 在琥珀酸负载的脂质体中重建，清楚地证明了琥珀酸的逆流和自交换活性。总之，这些发现表明 sucE1 编码一种在微需氧条件下诱导的新型琥珀酸输出蛋白，并且对于微需氧和厌氧条件下的琥珀酸生产都很重要。 (C) 2011 Elsevier B.V. 保留所有权利。
Corynebacterium glutamicum produces succinate from glucose via the reductive tricarboxylic acid cycle under microaerobic and anaerobic conditions. We identified a NCgl2130 gene of C. glutamicum as a novel succinate exporter that functions in succinate production, and designated sucE1. sucE1 expression levels were higher under microaerobic conditions than aerobic conditions, and overexpression or disruption of sucE1 respectively increased or decreased succinate productivity during fermentation. Under microaerobic conditions, the sucE1 disruptant sucE1 Delta showed 30% less succinate productivity and a lower sugar-consumption rate than the parental strain. Under anaerobic conditions, succinate production by sucE1 Delta ceased. The intracellular succinate and fructose-1,6-bisphosphate levels of sucE1 Delta under microaerobic conditions were respectively 1.7-fold and 1.6-fold higher than those of the parental strain, suggesting that loss of SucE1 function caused a failure of succinate removal from the cells, leading to intracellular accumulation that inhibited upstream sugar metabolism. Homology and transmembrane helix searches identified SucE1 as a membrane protein belonging to the aspartate: alanine exchanger (AAE) family. Partially purified 6x-histidine-tagged SucE1 (SucE1-[His](6)) reconstituted in succinate-loaded liposomes clearly demonstrated counterflow and self-exchange activities for succinate. Together, these findings suggest that sucE1 encodes a novel succinate exporter that is induced under microaerobic conditions, and is important for succinate production under both microaerobic and anaerobic conditions. (C) 2011 Elsevier B. V. All rights reserved.