The Fibro-purF motif is a putative structured noncoding RNA domain that was discovered previously in species of Fibrobacter by employing comparative sequence analysis methods. An updated bioinformatics search yielded a total of only 30 unique-sequence representatives, exclusively found upstream of the purF gene that codes for the enzyme amidophosphoribosyltransferase. This enzyme synthesizes the compound 5-phospho-D-ribosylamine (PRA), which is the first committed step in purine biosynthesis. The consensus model for Fibro-purF motif RNAs includes a predicted three-stem junction that carries numerous conserved nucleotide positions within the regions joining the stems. This architecture appears to be of sufficient size and complexity for the formation of the ligand-binding aptamer portion of a riboswitch. In this study, we conducted biochemical analyses of a representative Fibro-purF motif RNA to confirm that the RNA generally folds according to the predicted consensus model. However, due to the instability of PRA, binding of this ligand candidate by the RNA could not be direct assessed. Genetic analyses were used to demonstrate that Fibro-purF motif RNAs regulate gene expression in accordance with predicted PRA concentrations. Thus, our findings indicate that Fibro-purF motif RNAs are genetic regulation elements that likely suppress PRA biosynthesis when sufficient levels of this purine precursor are present.

中文翻译：

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一种罕见的细菌 RNA 基序与 purF 基因的调节有关，该基因编码的酶合成磷酸核糖胺

Fibro-purF 基序是一种推定的结构化非编码 RNA 结构域，以前通过比较序列分析方法在纤维杆菌属物种中发现。更新的生物信息学搜索总共只产生了 30 个独特的序列代表，仅在编码酰胺磷酸核糖基转移酶的 purF 基因上游发现。该酶合成化合物 5-磷酸-D-核糖胺 (PRA)，这是嘌呤生物合成的第一个关键步骤。Fibro-purF 基序 RNA 的共有模型包括一个预测的三茎连接，在连接茎的区域内携带许多保守的核苷酸位置。这种结构对于形成核糖开关的配体结合适体部分来说似乎具有足够的大小和复杂性。在这项研究中，我们对代表性的 Fibro-purF 基序 RNA 进行了生化分析，以确认 RNA 通常根据预测的共有模型折叠。然而，由于 PRA 的不稳定性，无法直接评估 RNA 与候选配体的结合。遗传分析用于证明 Fibro-purF 基序 RNA 根据预测的 PRA 浓度调节基因表达。因此，我们的研究结果表明 Fibro-purF 基序 RNA 是遗传调控元件，当这种嘌呤前体存在足够水平时，可能会抑制 PRA 生物合成。遗传分析用于证明 Fibro-purF 基序 RNA 根据预测的 PRA 浓度调节基因表达。因此，我们的研究结果表明 Fibro-purF 基序 RNA 是遗传调控元件，当这种嘌呤前体存在足够水平时，可能会抑制 PRA 生物合成。遗传分析用于证明 Fibro-purF 基序 RNA 根据预测的 PRA 浓度调节基因表达。因此，我们的研究结果表明 Fibro-purF 基序 RNA 是遗传调控元件，当这种嘌呤前体存在足够水平时，可能会抑制 PRA 生物合成。