Rangel-Mendoza Alejandra, Valenzuela-García Luz I, Robleto Eduardo A, Pedraza-Reyes Mario
Department of Biology, University of Guanajuato, Guanajuato 36050, Guanajuato, Mexico.
Department of Sustainable Engineering, Advanced Materials Research Center (CIMAV), Subsede-Durango, Durango 34147, Durango, Mexico.
Microorganisms. 2025 Apr 18;13(4):939. doi: 10.3390/microorganisms13040939.
During spore germination/outgrowth, the rehydration of the spore core and activation of aerobic metabolism can generate reactive oxygen species (ROS)-promoted DNA lesions that are repaired via the base excision repair pathway (BER). Accordingly, spores deficient in the AP-endonucleases (APEs) Nfo and ExoA exhibit a delayed outgrowth that is suppressed following disruption of the checkpoint protein DisA. Here, we report that DisA-independent DNA damage checkpoints operate during spore outgrowth. Consistent with this notion, spores lacking Nfo, ExoA, and Nth, which functions as an APE, did not suppress delayed outgrowth following disruption. Furthermore, in reference to the ∆ ∆ ∆ spores, spores deficient for these APEs and DisA displayed a significantly higher number of oxidative genetic lesions and failed to properly segregate its chromosome during the first round of replication in the outgrowth stage. Finally, we found that DisA promotes low-fidelity repair and replication events, as revealed by DNA-alkaline gel electrophoresis (AGE) as well as spontaneous and HO-promoted Rif mutagenesis. Overall, our results unveil the existence of DisA-independent DNA damage checkpoint(s) that are activated by genomic lesions of an oxidative nature during spore germination and outgrowth, ensuring a proper transition to vegetative growth.
在孢子萌发/生长过程中，孢子核心的再水化和有氧代谢的激活会产生活性氧物质（ROS）促进的DNA损伤，这些损伤通过碱基切除修复途径（BER）进行修复。因此，缺乏AP核酸内切酶（APE）Nfo和ExoA的孢子表现出延迟生长，这种延迟在检查点蛋白DisA被破坏后受到抑制。在此，我们报告在孢子生长过程中存在不依赖DisA的DNA损伤检查点。与这一观点一致，缺乏Nfo、ExoA和作为APE发挥作用的Nth的孢子在被破坏后并未抑制延迟生长。此外，相对于∆∆∆孢子，缺乏这些APE和DisA的孢子显示出显著更多的氧化遗传损伤，并且在生长阶段的第一轮复制过程中未能正确分离其染色体。最后，我们发现DisA促进低保真度的修复和复制事件，这通过DNA碱性凝胶电泳（AGE）以及自发和HO促进的利福平诱变得以揭示。总体而言，我们的结果揭示了不依赖DisA的DNA损伤检查点的存在，这些检查点在孢子萌发和生长过程中被氧化性质的基因组损伤激活，确保向营养生长的适当转变。
