Roberts Alexandra A, Copp Janine N, Marahiel Mohamed A, Neilan Brett A
The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales 2052, Australia.
Chembiochem. 2009 Jul 20;10(11):1869-77. doi: 10.1002/cbic.200900095.
The cyanobacterium Synechocystis sp. PCC6803 harbours one phosphopantetheinyl transferase (PPTase), Sppt. Protein modelling supported previous bioinformatics analyses, which suggested that Sppt is a Sfp-type PPTase with the potential to phosphopantetheinylate a broad range of carrier proteins from both primary and secondary metabolism. However, no natural products are synthesised by this species, which raises interesting evolutionary and functional questions. Phosphopantetheinylation assays and kinetic data demonstrate that Sppt was able to activate its cognate fatty acid synthesis carrier protein, SACP, but was unable to effectively activate various cyanobacterial carrier proteins from secondary metabolism or glycolipid biosynthesis pathways. To our knowledge, this is the first example of a PPTase with a Sfp-type structure, but with activity more closely resembling AcpS-type enzymes. The broad-range PPTase from Nodularia spumigena NSOR10 was introduced into Synechocystis sp. PCC6803 and was shown to activate a noncognate carrier protein, in vivo. This engineered strain could provide a future biotechnological platform for the heterologous expression of cyanobacterial biosynthetic gene clusters.
集胞藻6803（Synechocystis sp. PCC6803）含有一种磷酸泛酰巯基乙胺基转移酶（PPTase），即Sppt。蛋白质建模支持了之前的生物信息学分析，该分析表明Sppt是一种Sfp型PPTase，有可能对来自初级和次级代谢的多种载体蛋白进行磷酸泛酰巯基乙胺化修饰。然而，该物种并不合成天然产物，这引发了有趣的进化和功能问题。磷酸泛酰巯基乙胺化分析和动力学数据表明，Sppt能够激活其同源脂肪酸合成载体蛋白SACP，但无法有效激活来自次级代谢或糖脂生物合成途径的各种蓝藻载体蛋白。据我们所知，这是具有Sfp型结构但活性更类似于AcpS型酶的PPTase的首个实例。将来自泡沫节球藻（Nodularia spumigena）NSOR10的广谱PPTase导入集胞藻6803中，并证明其在体内能够激活一种非同源载体蛋白。这种工程菌株可为蓝藻生物合成基因簇的异源表达提供一个未来的生物技术平台。
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