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

点击翻译按钮获取中文摘要

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.