Jansen Joshua A, McCarthy Tom J, Soukup Garrett A, Soukup Juliane K
Department of Chemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, USA.
Nat Struct Mol Biol. 2006 Jun;13(6):517-23. doi: 10.1038/nsmb1094. Epub 2006 May 14.
The glmS ribozyme resides in the 5' untranslated region of glmS mRNA and functions as a catalytic riboswitch that regulates amino sugar metabolism in certain Gram-positive bacteria. The ribozyme catalyzes self-cleavage of the mRNA and ultimately inhibits gene expression in response to binding of glucosamine-6-phosphate (GlcN6P), the metabolic product of the GlmS protein. We have used nucleotide analog interference mapping (NAIM) and suppression (NAIS) to investigate backbone and nucleobase functional groups essential for ligand-dependent ribozyme function. NAIM using GlcN6P as ligand identified requisite structural features and potential sites of ligand and/or metal ion interaction, whereas NAIS using glucosamine as ligand analog revealed those sites that orchestrate recognition of ligand phosphate. These studies demonstrate that the ligand-binding site lies in close proximity to the cleavage site in an emerging model of ribozyme structure that supports a role for ligand within the catalytic core.
glmS核酶位于glmS mRNA的5'非翻译区，作为一种催化性核糖开关，调节某些革兰氏阳性菌中的氨基糖代谢。该核酶催化mRNA的自我切割，并最终在响应GlmS蛋白的代谢产物6-磷酸葡萄糖胺（GlcN6P）结合时抑制基因表达。我们利用核苷酸类似物干扰图谱（NAIM）和抑制（NAIS）来研究对于配体依赖性核酶功能至关重要的主链和核碱基官能团。以GlcN6P作为配体的NAIM确定了必需的结构特征以及配体和/或金属离子相互作用的潜在位点，而以葡萄糖胺作为配体类似物的NAIS揭示了那些协调配体磷酸基团识别的位点。这些研究表明，在支持配体在催化核心中发挥作用的核酶结构新模型中，配体结合位点紧邻切割位点。
