Department of Chemistry, Yale University, New Haven, Connecticut 06520-8103, USA.
Department of Biology, Howard University, Washington, D.C. 20059, USA.
RNA. 2019 Dec;25(12):1616-1627. doi: 10.1261/rna.072538.119. Epub 2019 Aug 29.
The motif is a riboswitch candidate present in various Acidobacteria species that was previously identified by bioinformatic analysis of bacterial DNA data sets. More than 100 unique representatives have been identified exclusively upstream of genes, which code for an enzyme in the biosynthetic pathway of the ubiquitous coenzyme NAD The architecture of motif RNAs suggests they use structurally similar tandem ligand-binding aptamer domains to control translation initiation. Biochemical analyses reveal that the first domain selectively binds ligands carrying an adenosine 5'-diphosphate (5' ADP) moiety, including NAD and its reduced form, NADH. Genetic analyses indicate that a tandem motif RNA suppresses gene expression when NAD is abundant, and that both aptamer domains are required for maximal gene regulation. However, we have not observed selective binding of the nicotinamide moiety of NAD or binding by the second putative aptamer in vitro, despite sequence and structural similarities between the tandem domains.
该基序是一种在各种酸杆菌物种中存在的核糖开关候选物，先前通过对细菌 DNA 数据集的生物信息学分析来鉴定。已经专门在编码普遍存在的辅酶 NAD 生物合成途径中的酶的基因上游鉴定出了 100 多个独特的代表。 motif RNA 的结构表明它们使用结构相似的串联配体结合适体结构域来控制翻译起始。生化分析表明，第一个结构域选择性地结合携带腺苷 5'-二磷酸（5'ADP）部分的配体，包括 NAD 和其还原形式 NADH。遗传分析表明，当 NAD 丰富时，串联 motif RNA 抑制基因表达，并且两个适体结构域都需要最大程度的基因调控。然而，尽管串联结构域之间存在序列和结构相似性，但我们尚未观察到 NAD 的烟酰胺部分的选择性结合或第二个假定适体的结合。
