Atrazine is an s-triazine-based herbicide that is used in many countries around the world in many millions of tons per year. A small number of organisms, such as Pseudomonas sp. strain ADP, have evolved to use this modified s-triazine as a food source, and the various genes required to metabolize atrazine can be found on a single plasmid. The atomic structures of seven of the eight proteins involved in the breakdown of atrazine by Pseudomonas sp. strain ADP have been determined by X-ray crystallography, but the structures of the proteins required by the cell to import atrazine for use as an energy source are still lacking. The structure of AtzT, a periplasmic binding protein that may be involved in the transport of a derivative of atrazine, 2-hydroxyatrazine, into the cell for mineralization, has now been determined. The structure was determined by SAD phasing using an ethylmercury phosphate derivative that diffracted X-rays to beyond 1.9 Å resolution. `Native' (guanine-bound) and 2-hydroxyatrazine-bound structures were also determined to high resolution (1.67 and 1.65 Å, respectively), showing that 2-hydroxyatrazine binds in a similar way to the purportedly native ligand. Structural similarities led to the belief that it may be possible to evolve AtzT from a purine-binding protein to a protein that can bind and detect atrazine in the environment.

中文翻译：

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AtzT（一种周质结合蛋白）的演变故事。

阿特拉津是一种基于均三嗪的除草剂，每年在世界许多国家使用数百万吨。少数生物，例如假单胞菌。ADP菌株已经进化到使用这种修饰的均三嗪作为食物来源，并且代谢莠去津所需的各种基因可以在单个质粒上找到。参与假单胞菌分解莠去津的八种蛋白质中的七种的原子结构。菌株ADP已通过X射线晶体学确定，但细胞输入莠去津作为能源所需的蛋白质结构仍然缺乏。AtzT 是一种周质结合蛋白，可能参与莠去津衍生物 2-羟基莠去津转运至细胞内进行矿化，现已确定其结构。该结构是通过使用磷酸乙基汞衍生物的 SAD 定相来确定的，该衍生物的 X 射线衍射分辨率超过 1.9 Å。“天然”（鸟嘌呤结合）和 2-羟基莠去津结合结构也被确定为高分辨率（分别为 1.67 和 1.65 Å），表明 2-羟基莠去津以类似的方式与所谓的天然配体结合。结构上的相似性使人们相信，AtzT 有可能从嘌呤结合蛋白进化为可以结合并检测环境中莠去津的蛋白。