Enoyl-CoA hydratase mediates polyhydroxyalkanoate mobilization in Haloferax mediterranei.
Enoyl-CoA hydratase mediates polyhydroxyalkanoate mobilization in Haloferax mediterranei.
复制标题
烯酰辅酶 A 水合酶介导地中海 Haloferax 中的聚羟基脂肪酸酯动员
DOI：
10.1038/srep24015
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发表时间：
2016-04-07
影响因子：
4.6
通讯作者：
Xiang H
中科院分区：
文献类型：
--
作者：
Liu G;Cai S;Hou J;Zhao D;Han J;Zhou J;Xiang H
聚羟基烷酸酯（polyhydroxyalkanoate，PHA）的积累和动员是盐古菌适应碳源多变的高盐环境的最普遍机制之一，但对任何盐古菌而言，PHA的动员途径尚不清楚。本研究对地中海盐藻中5种推测的（R）-特异性烯酰辅酶A水合酶（R-ECH）（PhaJ 1 ~ PhaJ 5）的功能进行了深入研究。通过基因缺失和互补，我们证明，只有某些这些ECH有轻微的贡献聚（3-羟基丁酸-co-3-羟基戊酸）（PHBV）的生物合成。但值得注意的是，PhaJ 1，唯一的R-ECH是与PHA颗粒，被证明参与PHA动员在这个盐古菌。PhaJ 1催化PHA降解的共同产物（R）-3-羟酰辅酶A脱水生成β-氧化循环的中间产物烯酰辅酶A，从而将PHA动员与H.医生。PHA动员条件下β-氧化关键基因的上调以及β-氧化途径抑制后PHA降解的明显抑制进一步表明了这种联系。有趣的是，96%的含phaJ的盐古菌物种同时具有phaC（编码PHA合酶）和β-氧化的全套基因，这意味着通过β-氧化循环在PHA中动员碳储存在盐古菌中是普遍的。
Although polyhydroxyalkanoate (PHA) accumulation and mobilization are one of the most general mechanisms for haloarchaea to adapt to the hypersaline environments with changeable carbon sources, the PHA mobilization pathways are still not clear for any haloarchaea. In this study, the functions of five putative (R)-specific enoyl-CoA hydratases (R-ECHs) in Haloferax mediterranei, named PhaJ1 to PhaJ5, respectively, were thoroughly investigated. Through gene deletion and complementation, we demonstrated that only certain of these ECHs had a slight contribution to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biosynthesis. But significantly, PhaJ1, the only R-ECH that is associated with PHA granules, was shown to be involved in PHA mobilization in this haloarchaeon. PhaJ1 catalyzes the dehydration of (R)-3-hydroxyacyl-CoA, the common product of PHA degradation, to enoyl-CoA, the intermediate of the β-oxidation cycle, thus could link PHA mobilization to β-oxidation pathway in H. mediterranei. This linkage was further indicated from the up-regulation of the key genes of β-oxidation under the PHA mobilization condition, as well as the obvious inhibition of PHA degradation upon inhibition of the β-oxidation pathway. Interestingly, 96% of phaJ-containing haloarchaeal species possess both phaC (encoding PHA synthase) and the full set genes of β-oxidation, implying that the mobilization of carbon storage in PHA through the β-oxidation cycle would be general in haloarchaea.