Fluorothreonyl-tRNA deacylase prevents mistranslation in the organofluorine producer Streptomyces cattleya
Fluorothreonyl-tRNA deacylase prevents mistranslation in the organofluorine producer Streptomyces cattleya
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DOI：
10.1073/pnas.1711482114
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发表时间：
2017-11-07
影响因子：
11.1
通讯作者：
Chang, Michelle C. Y.
中科院分区：
文献类型：
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作者：
McMurry, Jonathan L.;Chang, Michelle C. Y.
氟是一种具有不寻常特性的元素，在合成小分子的设计中具有重要的实用性，从治疗到材料。相比之下，迄今为止只发现了少数由活生物体产生的氟化化合物，其中大部分来自首次在卡特兰链霉菌中发现的氟乙酸/氟代苏氨酸生物合成途径。虽然氟乙酸盐长期以来被认为是三羧酸循环的抑制剂，但氨基酸氟代苏氨酸的命运仍然没有得到很好的理解。在这里，我们表明，氟代苏氨酸可以被错误地纳入蛋白质中的蛋白质氨基酸苏氨酸的地方。我们已经确定了两个保守的蛋白质的有机氟生物合成位点，FthB和FthC，参与管理氟代菊酯毒性。使用生物化学，遗传学，生理学和蛋白质组学研究的组合，我们表明，FthB是一种反式作用的转移RNA（tRNA）编辑蛋白，其水解fluorothreonyl-tRNA的效率比threonyl-RNA高670倍，并在fluorothreonyl-RNA运输中分配FthC的作用。虽然反式作用tRNA编辑蛋白已被发现可以抵消tRNA与常见的近同源氨基酸的错酰化，但它们的作用尚未在次级代谢的背景下描述。在这方面，将tRNA编辑蛋白募集到生物合成簇中可能使产生专门氨基酸的途径得以进化，从而增加了天然产物结构的多样性，同时也降低了随之而来的误译风险。
Fluorine is an element with unusual properties that has found significant utility in the design of synthetic small molecules, ranging from therapeutics to materials. In contrast, only a few fluorinated compounds made by living organisms have been found to date, most of which derive from the fluoroacetate/fluorothreonine biosynthetic pathway first discovered in Streptomyces cattleya. While fluoroacetate has long been known to act as an inhibitor of the tricarboxylic acid cycle, the fate of the amino acid fluorothreonine is still not well understood. Here, we show that fluorothreonine can be misincorporated into protein in place of the proteinogenic amino acid threonine. We have identified two conserved proteins from the organofluorine biosynthetic locus, FthB and FthC, that are involved in managing fluorothreonine toxicity. Using a combination of biochemical, genetic, physiological, and proteomic studies, we show that FthB is a trans-acting transfer RNA (tRNA) editing protein, which hydrolyzes fluorothreonyl-tRNA 670-fold more efficiently than threonyl-RNA, and assign a role to FthC in fluorothreonine transport. While trans-acting tRNA editing proteins have been found to counteract the misacylation of tRNA with commonly occurring nearcognate amino acids, their role has yet to be described in the context of secondary metabolism. In this regard, the recruitment of tRNA editing proteins to biosynthetic clusters may have enabled the evolution of pathways to produce specialized amino acids, thereby increasing the diversity of natural product structure while also attenuating the risk of mistranslation that would ensue.