AdeR, a PucR-Type Transcription Factor, Activates Expression of L-Alanine Dehydrogenase and Is Required for Sporulation of Bacillus subtilis
AdeR, a PucR-Type Transcription Factor, Activates Expression of L-Alanine Dehydrogenase and Is Required for Sporulation of Bacillus subtilis
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DOI：
10.1128/jb.00778-12
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发表时间：
2012-09-01
影响因子：
3.2
通讯作者：
Shaw, Gwo-Chyuan
中科院分区：
文献类型：
--
作者：
Lin, Ta-Hui;Wei, Guei-Tsung;Shaw, Gwo-Chyuan
枯草芽孢杆菌 ald 基因编码 L-丙氨酸脱氢酶，该酶催化 L-丙氨酸的 NAD(+) 依赖性脱氨基作用生成丙酮酸以产生能量，并且是正常孢子形成所必需的。 ald 的转录是由丙氨酸诱导的，但丙氨酸诱导的机制仍不清楚。在这里，我们报道位于 ald 上游的一个基因（以前是 yukF，现在指定为 adeR）对于 ald 的基础表达和丙氨酸诱导表达至关重要。 adeR基因的破坏导致孢子形成缺陷，而adeR突变与完整的adeR基因的互补恢复了孢子形成能力。 adeR 表达不受自动调节和丙氨酸诱导的影响。删除和突变分析表明，以 ald 转录起始位点为中心的反向重复序列是 ald 表达所必需的，并且也可能充当不依赖于 rho 的转录终止子。电泳迁移率变动分析表明，纯化的带有 His 标签的 AdeR 是一种特异性 DNA 结合蛋白，并且这种反向重复序列是 AdeR 结合所必需的。 AdeR 与其他细菌的 ald 基因的已知转录激活因子没有显着的氨基酸序列相似性。 AdeR 似乎是转录调节因子 PucR 家族的成员。其功能未知的直向同源物存在于其他一些芽孢杆菌属物种中。总的来说，这些发现支持这样的观点，即 AdeR 是一种转录激活剂，它根据丙氨酸的可用性介导 ald 表达，并且对于枯草芽孢杆菌的正常孢子形成很重要。
The Bacillus subtilis ald gene encodes L-alanine dehydrogenase, which catalyzes the NAD(+)-dependent deamination of L-alanine to pyruvate for the generation of energy and is required for normal sporulation. The transcription of ald is induced by alanine, but the mechanism underlying alanine induction remains unknown. Here we report that a gene (formerly yukF and now designated adeR) located upstream of ald is essential for the basal and alanine-inducible expression of ald. The disruption of the adeR gene caused a sporulation defect, whereas the complementation of an adeR mutation with an intact adeR gene restored the sporulation ability. adeR expression was not subject to autoregulation and alanine induction. Deletion and mutation analyses revealed that an inverted repeat, centered at position -74.5 relative to the transcriptional initiation site of ald, was required for ald expression and also likely served as a rho-independent transcription terminator. Electrophoretic mobility shift assays showed that purified His-tagged AdeR was a specific DNA-binding protein and that this inverted repeat was required for AdeR binding. AdeR shows no significant amino acid sequence similarity to the known transcriptional activators of ald genes from other bacteria. AdeR appears to be a member of the PucR family of transcriptional regulators. Its orthologs of unknown function are present in some other Bacillus species. Collectively, these findings support the notion that AdeR is a transcriptional activator which mediates ald expression in response to alanine availability and is important for normal sporulation in B. subtilis.