本公众号主要跟踪各大植物学期刊最新文献，比如Nature Plants，Molecular Plant，The Plant Cell，New Phytologist，Plant Physiology 等。

尤其以Nature Plants 为主，该期刊每一篇文献必定跟踪阅读。

本文于2017年11月27日在线发表于Nature Plants，原文题目如下：

Non-specific activities of the major herbicide-resistance gene BAR

双丙氨磷抗性（BAR）和膦丝菌素乙酰转移酶（PAT）基因通过N-乙酰化传递对广谱除草剂膦丝菌素（也称作草铵膦）的抗性，已经在基础植物研究和基因工程作物中广泛使用。虽然早期的体外酶测定表明，重组BAR和PAT底物对膦丝菌素具有偏好性，这种偏好性高于对20种蛋白质氨基酸的，但已经看到含BAR的转基因在植物中的间接作用，包括氨基酸水平的修饰，但是没有鉴定它们的直接作用。结合代谢组学，植物遗传学和生物化学方法，结果显示，在几种植物物种中，转基因BAR确实将两种植物内源氨基酸氨基，己二酸和色氨酸，转化为它们各自的N-乙酰化产物。我们报道了BAR的晶体结构，并进一步描述了其底物选择性和催化机理的结构基础。通过结构引导的蛋白质工程，我们产生了几个BAR变体，与其野生型对应物相比，在体内显示出显着减少的非特异性活性。酶的转基因表达可导致由酶混乱引起的随意的脱靶代谢。在机械水平上理解这种现象，可以以异源表达的酶为特征，最大限度的促进绝缘系统的设计。

Bialaphos resistance (BAR) and phosphinothricin acetyltransferase (PAT) genes, which convey resistance to the broad-spectrum herbicide phosphinothricin (also known as glufosinate) via N-acetylation, have been globally used in basic plant research and genetically engineered crops. Although early in vitro enzyme assays showed that recombinant BAR and PAT exhibit substrate preference toward phosphinothricin over the 20 proteinogenic amino acids, indirect effects of BAR-containing transgenes in planta, including modified amino acid levels, have been seen but without the identification of their direct causes. Combining metabolomics, plant genetics and biochemical approaches, we show that transgenic BAR indeed converts two plant endogenous amino acids, aminoadipate and tryptophan, to their respective N-acetylated products in several plant species. We report the crystal structures of BAR, and further delineate structural basis for its substrate selectivity and catalytic mechanism. Through structure-guided protein engineering, we generated several BAR variants that display significantly reduced non-specific activities compared with its wild-type counterpart in vivo. The transgenic expression of enzymes can result in unintended off-target metabolism arising from enzyme promiscuity. Understanding such phenomena at the mechanistic level can facilitate the design of maximally insulated systems featuring heterologously expressed enzymes.

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