CugP Is a Novel Ubiquitous Non-GalU-Type Bacterial UDP-Glucose Pyrophosphorylase Found in Cyanobacteria
CugP Is a Novel Ubiquitous Non-GalU-Type Bacterial UDP-Glucose Pyrophosphorylase Found in Cyanobacteria
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DOI：
10.1128/jb.01591-14
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发表时间：
2014-04
影响因子：
3.2
通讯作者：
Kaisei Maeda;R. Narikawa;M. Ikeuchi
中科院分区：
文献类型：
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作者：
Kaisei Maeda;R. Narikawa;M. Ikeuchi
摘要 UDP-葡萄糖焦磷酸化酶从 UTP 和葡萄糖 1-磷酸合成 UDP-葡萄糖，几乎存在于所有物种中。大多数细菌具有 GalU 型 UDP-葡萄糖焦磷酸化酶，而许多蓝藻物种则没有。在某些蓝细菌中，尽管不存在GalU型UDP-葡萄糖焦磷酸化酶，但UDP-葡萄糖仍被用作合成胞外多糖纤维素的底物。因此，蓝藻中应该存在一种未表征的UDP-葡萄糖焦磷酸化酶。在这里，我们证明所有蓝细菌都拥有非 GalU 型细菌 UDP-葡萄糖焦磷酸化酶，即 CugP，它是核苷酸三磷酸转移酶超家族中的一个新家族。表达的重组集胞藻。菌株 PCC 6803 CugP 具有对 UTP 和葡萄糖 1-磷酸高度特异性的焦磷酸化酶活性。事实上，集胞藻中的 CugP 基因不能被完全删除。 PCC 6803 表明其作为半乳糖脂合成底物供应商的核心作用。半乳糖脂是光合作用类囊体膜的主要成分，对光合作用很重要。基于系统发育分析，这种CugP型UDP-葡萄糖焦磷酸化酶最近可能水平转移到某些非蓝藻细菌中。
ABSTRACT UDP-glucose pyrophosphorylase synthesizes UDP-glucose from UTP and glucose 1-phosphate and exists in almost all species. Most bacteria possess a GalU-type UDP-glucose pyrophosphorylase, whereas many cyanobacteria species do not. In certain cyanobacteria, UDP-glucose is used as a substrate for synthesis of exopolysaccharide cellulose in spite of the absence of GalU-type UDP-glucose pyrophosphorylase. Therefore, there should be an uncharacterized UDP-glucose pyrophosphorylase in cyanobacteria. Here, we show that all cyanobacteria possess a non-GalU-type bacterial UDP-glucose pyrophosphorylase, i.e., CugP, a novel family in the nucleotide triphosphate transferase superfamily. The expressed recombinant Synechocystis sp. strain PCC 6803 CugP had pyrophosphorylase activity that was highly specific for UTP and glucose 1-phosphate. The fact that the CugP gene cannot be deleted completely in Synechocystis sp. PCC 6803 suggests its central role as the substrate supplier for galactolipid synthesis. Galactolipids are major constituents of the photosynthetic thylakoid membrane and important for photosynthetic activity. Based on phylogenetic analysis, this CugP-type UDP-glucose pyrophosphorylase may have recently been horizontally transferred to certain noncyanobacteria.