Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
RNA. 2010 Mar;16(3):474-81. doi: 10.1261/rna.1965310. Epub 2010 Jan 27.
Dicer or Dicer-like (DCL) protein is a catalytic component involved in microRNA (miRNA) or small interference RNA (siRNA) processing pathway, whose fragment structures have been partially solved. However, the structure and function of the unique DUF283 domain within dicer is largely unknown. Here we report the first structure of the DUF283 domain from the Arabidopsis thaliana DCL4. The DUF283 domain adopts an alpha-beta-beta-beta-alpha topology and resembles the structural similarity to the double-stranded RNA-binding domain. Notably, the N-terminal alpha helix of DUF283 runs cross over the C-terminal alpha helix orthogonally, therefore, N- and C-termini of DUF283 are in close proximity. Biochemical analysis shows that the DUF283 domain of DCL4 displays weak dsRNA binding affinity and specifically binds to double-stranded RNA-binding domain 1 (dsRBD1) of Arabidopsis DRB4, whereas the DUF283 domain of DCL1 specifically binds to dsRBD2 of Arabidopsis HYL1. These data suggest a potential functional role of the Arabidopsis DUF283 domain in target selection in small RNA processing.
Dicer 或 Dicer 样 (DCL) 蛋白是一种参与 microRNA (miRNA) 或小干扰 RNA (siRNA) 加工途径的催化成分，其片段结构已部分得到解决。然而，Dicer 内独特的 DUF283 结构域的结构和功能在很大程度上尚不清楚。在这里，我们报告了来自拟南芥 DCL4 的 DUF283 结构域的第一个结构。DUF283 结构域采用 alpha-beta-beta-beta-alpha 拓扑结构，类似于双链 RNA 结合结构域的结构相似性。值得注意的是，DUF283 的 N 端 alpha 螺旋垂直穿过 C 端 alpha 螺旋，因此 N 端和 C 端非常接近。生化分析表明，DCL4 的 DUF283 结构域显示出较弱的 dsRNA 结合亲和力，并特异性结合拟南芥 DRB4 的双链 RNA 结合结构域 1 (dsRBD1)，而 DCL1 的 DUF283 结构域特异性结合拟南芥 HYL1 的 dsRBD2。这些数据表明拟南芥 DUF283 结构域在小 RNA 加工中的靶标选择中可能具有潜在的功能作用。
