Lang Kevin S, Hall Ashley N, Merrikh Christopher N, Ragheb Mark, Tabakh Hannah, Pollock Alex J, Woodward Joshua J, Dreifus Julia E, Merrikh Houra
Department of Microbiology, Health Sciences Building - J-wing, University of Washington, Seattle, WA, 98195.
Department of Microbiology, Health Sciences Building - J-wing, University of Washington, Seattle, WA, 98195; Molecular and Cellular Biology Program, University of Washington, Seattle, WA, 98195.
Cell. 2017 Aug 10;170(4):787-799.e18. doi: 10.1016/j.cell.2017.07.044.
Replication-transcription collisions shape genomes, influence evolution, and promote genetic diseases. Although unclear why, head-on transcription (lagging strand genes) is especially disruptive to replication and promotes genomic instability. Here, we find that head-on collisions promote R-loop formation in Bacillus subtilis. We show that pervasive R-loop formation at head-on collision regions completely blocks replication, elevates mutagenesis, and inhibits gene expression. Accordingly, the activity of the R-loop processing enzyme RNase HIII at collision regions is crucial for stress survival in B. subtilis, as many stress response genes are head-on to replication. Remarkably, without RNase HIII, the ability of the intracellular pathogen Listeria monocytogenes to infect and replicate in hosts is weakened significantly, most likely because many virulence genes are head-on to replication. We conclude that the detrimental effects of head-on collisions stem primarily from excessive R-loop formation and that the resolution of these structures is critical for bacterial stress survival and pathogenesis.
复制-转录冲突塑造基因组、影响进化并促进遗传疾病。尽管原因不明，但同向转录（滞后链基因）对复制具有特别的干扰作用，并会促进基因组不稳定。在此，我们发现同向冲突会促进枯草芽孢杆菌中R环的形成。我们表明，在同向冲突区域普遍形成的R环会完全阻断复制、提高突变率并抑制基因表达。因此，R环加工酶RNase HIII在冲突区域的活性对于枯草芽孢杆菌的应激生存至关重要，因为许多应激反应基因与复制同向。值得注意的是，缺乏RNase HIII时，细胞内病原体单核细胞增生李斯特菌在宿主中感染和复制的能力会显著减弱，这很可能是因为许多毒力基因与复制同向。我们得出结论，同向冲突的有害影响主要源于过度的R环形成，而这些结构的消解对于细菌的应激生存和致病机制至关重要。
