FabG can function as PhaB for poly-3-hydroxybutyrate biosynthesis in photosynthetic cyanobacteria Synechocystis sp PCC 6803
FabG can function as PhaB for poly-3-hydroxybutyrate biosynthesis in photosynthetic cyanobacteria Synechocystis sp PCC 6803
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FabG 可充当光合蓝细菌集胞藻 PCC 6803 中聚 3-羟基丁酸酯生物合成的 PhaB
DOI：
10.1080/21655979.2017.1317574
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发表时间：
2017
期刊：
影响因子：
4.9
通讯作者：
Xue Song
中科院分区：
文献类型：
--
作者：
Zhang Haowei;Liu Yinghui;Yao Changhong;Cao Xupeng;Tian Jing;Xue Song
利用光合蓝藻生产聚3-羟基丁酸酯（PHB）是生物降解塑料工业中一种潜在的可持续生产方法。β-酮脂酰-ACP还原酶（FabG），来自光合蓝细菌集胞藻。PCC 6803（SpFabG）是脂肪酸生物合成途径中的第一个NADPH依赖性还原酶。它的结构与乙酰乙酰辅酶A还原酶（SpPhaB）相似，在体外可替代SpPhaB进行乙酰乙酰辅酶A的还原。但SpFabG在脂肪酸合成中的具体功能以及SpFabG是否参与了PHB的合成尚不清楚。在这项研究中，SpFabG在脂肪酸合成中的作用首次在体内通过敲低和过表达abG来验证。结果表明，SpFabG是必需的，但不限速脂肪酸的生物合成。使用乙酰乙酰辅酶A作为底物的SpFabG的生物化学表征显示，最适温度、最适pH、Kmandkcat分别为30°C、7、2.30 mM和19.85 s-1，这例示了SpFabG以相对低的亲和力和弱的催化效率还原乙酰乙酰辅酶A的能力。SpFabG在体内的功能分析表明，SpFabG能够在缺氮条件下部分地补充SpPhaB，并且过量表达abG导致部分碳通量从脂肪酸转向PHB合成。
The production of poly-3-hydroxybutyrate (PHB) by photosynthetic cyanobacteria is a potentially sustainable production method for the biodegradable plastics industry. β-Ketoacyl-ACP reductase (FabG), from the photosynthetic cyanobacteriumSynechocystissp. PCC 6803 (SpFabG), is the first NADPH-dependent reductase in the fatty acid biosynthesis pathway. Its structure is similar to that of acetoacetyl-CoA reductase (SpPhaB), which is critical for PHB synthesis and can replace SpPhaB for acetoacetyl-CoA reductionin vitro. However, the specific function of SpFabG in fatty acid synthesis and whether SpFabG could participate in PHB synthesisin vivowere not yet clear. In this study, the role of SpFabG in fatty acid synthesis was first verifiedin vivoby knocking down and overexpressing offabG. It was shown that SpFabG was essential yet not rate-limiting for fatty acid biosynthesis. The biochemical characterization of SpFabG using acetoacetyl-CoA as the substrate showed that the optimum temperature, optimum pH,Kmandkcatwere 30°C, 7, 2.30 mM, and 19.85 s−1, respectively, which exemplified the ability of SpFabG to reduce acetoacetyl-CoA with a relatively low affinity and weak catalytic efficiency. Functional analysis of SpFabGin vivoindicated that SpFabG was able to partially complement SpPhaB under nitrogen-deprived conditions, and overexpression offabGled to the diversion of partial carbon flux from fatty acid toward PHB synthesis.