PDF(Pubmed)
Abstract：
Oligoribonuclease (Orn), a member of the DEDDh superfamily, can hydrolyse 2-5 nt nanoRNAs to mononucleotides. It is involved in maintaining the intracellular levels of RNA, c-di-GMP signalling and transcription initiation in many bacterial species. Here, the crystal structure of Orn from Vibrio cholerae O1 El Tor (VcOrn) is reported at a resolution of 1.7 Å. VcOrn, which consists of nine α-helices and six β-strands, crystallizes with a single monomer in the asymmetric unit but forms a homodimer via crystallographic twofold symmetry. Electron density is observed in the active pocket that corresponds to an intersubunit N-terminal expression tag with sequence GPLGSHHH. The positively charged N-terminal tag binds in the negatively charged nucleotide-binding pocket with a buried surface area of ∼500 Å2. The N-terminal tag interacts with VcOrn via π-π stacking with two conserved residues involved in nucleotide binding, as well as via salt bridges and hydrogen bonds. The structure reported here reveals that the active pocket can accommodate polypeptides in addition to nucleotides, thus providing an important starting point for investigation into substrate modification and inhibitor design targeting VcOrn.
摘要：
寡核糖核酸酶(Orn),DEDDh超家族的一员,可以将2-5个核苷酸的nanoRNAs水解为单核苷酸。它参与维持RNA的细胞内水平，许多细菌物种中的c-di-GMP信号传导和转录起始。这里,据报道，霍乱弧菌O1ElTor（VcOrn）的Orn的晶体结构为1.7µ。VcOrn,由九个α螺旋和六个β链组成，在不对称单元中与单个单体结晶，但通过晶体学双重对称形成同源二聚体。在对应于具有序列GPLGSHHH的亚基间N-末端表达标签的活性袋中观察到电子密度。带正电荷的N末端标签结合在带负电荷的核苷酸结合袋中，其埋藏表面积为500〜2。N端标签通过π-π堆叠与VcOrn相互作用，两个保守残基参与核苷酸结合，以及通过盐桥和氢键。这里报道的结构表明，除了核苷酸之外，活性口袋还可以容纳多肽，从而为研究底物修饰和靶向VcOrn的抑制剂设计提供了重要的起点。
