惊鸿 (2024-01-31 20:12):
#paper Pub Date  : 2024-01-15 DOI : 10.1016/j.str.2023.12.012 tRNA 衍生片段 (tRF) 已成为免疫调节的关键参与者。一些RNase A 超家族成员参与 tRF 群体的形成。通过比较野生型和敲除型巨噬细胞系,我们之前的工作揭示了 RNase 2 可以选择性切割 tRNA。在这里,我们通过筛选合成 tRNA、单突变体和反密码子环 DNA/RNA 发夹来确认体外蛋白质切割模式。通过对 tRF 产物进行测序,我们确定了重组 RNase 2 的切割选择性,在 B 1 (U/C) 和 B 2 (A) 位点具有碱基特异性,这与之前的细胞研究一致。最后,通过MD模拟预测了蛋白质-发夹复合物。结果揭示了 α1、环 3 和环 4 以及 β6 RNase 2 区域的贡献,其中残基 Arg36/Asn39/Gln40/Asn65/Arg68/Arg132 提供相互作用,跨越对反密码子至关重要的P -1到 P 2位点循环识别。对 RNase 2 特异性 tRF 生成的了解可能会指导传染病和免疫相关疾病的新治疗方法。
Structural determinants for tRNA selective cleavage by RNase 2/EDN
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Abstract:
tRNA-derived fragments (tRFs) have emerged as key players of immunoregulation. Some RNase A superfamily members participate in the shaping of the tRFs population. By comparing wild-type and knockout macrophage cell lines, our previous work revealed that RNase 2 can selectively cleave tRNAs. Here, we confirm the in vitro protein cleavage pattern by screening of synthetic tRNAs, single-mutant variants, and anticodon-loop DNA/RNA hairpins. By sequencing of tRF products, we identified the cleavage selectivity of recombinant RNase 2 with base specificity at B (U/C) and B (A) sites, consistent with a previous cellular study. Lastly, protein-hairpin complexes were predicted by MD simulations. Results reveal the contribution of the α1, loop 3 and loop 4, and β6 RNase 2 regions, where residues Arg36/Asn39/Gln40/Asn65/Arg68/Arg132 provide interactions, spanning from P to P sites that are essential for anticodon loop recognition. Knowledge of RNase 2-specific tRFs generation might guide new therapeutic approaches for infectious and immune-related diseases.
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