S1 nuclease from Aspergillus oryzae is a single-strand-specific nuclease from the S1/P1 family that is utilized in biochemistry and biotechnology. S1 nuclease is active on both RNA and DNA but with differing catalytic efficiencies. This study clarifies its catalytic properties using a thorough comparison of differences in the binding of RNA and DNA in the active site of S1 nuclease based on X-ray structures, including two newly solved complexes of S1 nuclease with the products of RNA cleavage at atomic resolution. Conclusions derived from this comparison are valid for the whole S1/P1 nuclease family. For proper model building and refinement, multiple lattice-translocation defects present in the measured diffraction data needed to be solved. Two different approaches were tested and compared. Correction of the measured intensities proved to be superior to the use of the dislocation model of asymmetric units with partial occupancy of individual chains. As the crystals suffered from multiple lattice translocations, equations for their correction were derived de novo. The presented approach to the correction of multiple lattice-translocation defects may help to solve similar problems in the field of protein X-ray crystallography.

中文翻译：

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尽管存在多个晶格易位缺陷，但 S1 核酸酶复合物的原子分辨率研究揭示了 RNA 与酶相互作用的细节

来自米曲霉的 S1 核酸酶是一种来自 S1/P1 家族的单链特异性核酸酶，用于生物化学和生物技术。S1 核酸酶对 RNA 和 DNA 均有活性，但催化效率不同。本研究通过对基于 X 射线结构的 S1 核酸酶活性位点中 RNA 和 DNA 结合的差异进行全面比较，阐明了其催化特性，包括两个新解决的 S1 核酸酶复合物与原子分辨率下 RNA 切割产物的复合物. 从该比较得出的结论适用于整个 S1/P1 核酸酶家族。为了正确建立和完善模型，需要解决测量的衍射数据中存在的多个晶格易位缺陷。测试和比较了两种不同的方法。事实证明，对测量强度的校正优于使用单个链部分占据的不对称单元的位错模型。由于晶体遭受多次晶格易位，因此导出了校正方程从头开始。所提出的校正多个晶格易位缺陷的方法可能有助于解决蛋白质 X 射线晶体学领域中的类似问题。