The 2H phosphoesterase superfamily (2H family) proteins are widely conserved among organisms. The 2H family is classified into several subgroups, including YjcG-like proteins whose enzymatic activity has not been reported. In the present study, we found that two YjcG-like proteins (Staphylococcus aureus SA0873 and Bacillus subtilis YjcG) have 2'-CPDase activity that hydrolyzes a 2',3'-cyclic nucleotide, thereby producing a nucleotide with a 3'-phosphate. The SA0873 protein selectively hydrolyzes a 2',3'-cyclic nucleotide with a purine base. Four SA0873 mutant proteins (H34A, T36A, H115A, and T117A), in which alanine was substituted for amino acid residues in the HxT/Sx motifs that are conserved in the 2H family, abolished the 2'-CPDase activity. Comparison of three-dimensional structures between the YjcG-like proteins with 2'-CPDase activity and another 2H family subgroup, LigT/2'-5' RNA ligase-like proteins with 3'-CPDase activity, revealed that the orientation of the substrate binding pocket is reversed between the two groups. Our findings revealed that YjcG-like proteins not only have a substrate-binding pocket different from that of LigT/2'-5' RNA ligase-like proteins, but they also have 2'-CPDase activity.

中文翻译：

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具有2'-CPDase活性的2H磷酸酯酶超家族蛋白的鉴定。

2H磷酸酯酶超家族（2H家族）蛋白质在生物体中被广泛保存。2H家族分为几个亚组，包括尚未报道其酶促活性的YjcG样蛋白。在本研究中，我们发现两个YjcG样蛋白（金黄色葡萄球菌SA0873和枯草芽孢杆菌YjcG）具有2'-CPDase活性，可水解2'，3'-环状核苷酸，从而产生具有3'-磷酸的核苷酸。SA0873蛋白用嘌呤碱基选择性水解2'，3'-环核苷酸。四种SA0873突变蛋白（H34A，T36A，H115A和T117A）用2H家族保守的HxT / Sx模体中的丙氨酸取代了氨基酸残基，从而废除了2'-CPDase活性。比较具有2'-CPDase活性的YjcG样蛋白和另一个具有3'-CPDase活性的2H家族亚群LigT / 2'-5'RNA连接酶样蛋白的三维结构，揭示了底物的方向两组之间的装订袋颠倒了。我们的发现表明，YjcG样蛋白不仅具有不同于LigT / 2'-5'RNA连接酶样蛋白的底物结合口袋，而且还具有2'-CPDase活性。