Elucidation of the molecular mechanisms underlying the decryptification of the gudB gene in the Gram-positive model bacterium Bacillus subtilis

谷氨酸是任何活细胞的中心代谢物.因此，维持细胞内谷氨酸浓度恒定至关重要。这是通过调节谷氨酸的生物合成和降解取决于可用的营养素。革兰氏阳性模式菌枯草芽孢杆菌具有在基因组水平上响应谷氨酸代谢扰动的显著能力。缺乏功能性谷氨酸脱氢酶RocG的细菌迅速激活隐藏的gudB基因，并且抑制突变体合成功能性谷氨酸脱氢酶GudB，其可以在功能上取代RocG。突变事件是基于隐藏gudB基因中的完美直接重复的一个重复单元的切除。最近，我们发现转录是gudB基因激活的主要原因。我们还观察到，转录修复偶联因子Mfd和两个RNase H旁系同源物解决RNA：DNA双链体有助于直接重复不稳定性B。枯草杆菌。最后，我们发现，translesion DNA聚合酶的活性参与切除无活性gudB基因中的直接重复序列的一个重复单元。在拟议的项目中，我们希望阐明这些因素如何共同作用，以支持转录严重影响细菌中直接重复完整性的假设。

Glutamate is a central metabolite any living cell. Therefore, it is crucial to maintain the intracellular glutamate concentration constant. This is achieved by adjusting glutamate biosynthesis and degradation depending on the available nutrients. The Gram-positive model bacterium Bacillus subtilis has the remarkable ability to respond to perturbations of glutamate metabolism at the genome level. Bacteria lacking the functional glutamate dehydrogenase RocG rapidly activate the cryptic gudB gene and the suppressor mutants synthesize the functional glutamate dehydrogenase GudB, which may functionally replace RocG. The mutational event is based on the excision of one repeat unit of a perfect direct repeat in the cryptic gudB gene. Recently, we found that transcription is the major cause for the activation of the gudB gene. We also observed that the transcription-repair coupling factor Mfd and two RNase H paralogs resolving RNA:DNA duplexes contribute to direct repeat instability in B. subtilis. Finally, we found that the activity of a translesion DNA polymerase is involved in the excision of one repeat unit of the direct repeat in the inactive gudB gene. In the proposed project we want to elucidate how these factors act together to support the hypothesis that transcription severely influences direct repeat integrity in bacteria.