摘要：Abstract During sporulation Bacillus subtilis Mfd couples transcription to nucleotide excision repair (NER) to eliminate DNA distorting lesions. Here, we report a significant decline in sporulation following Mfd disruption, which was manifested in the absence of external DNA-damage suggesting that spontaneous lesions activate the function of Mfd for an efficient sporogenesis. Accordingly, a dramatic decline in sporulation efficiency took place in a B. subtilis strain lacking Mfd and the repair/prevention guanine oxidized (GO) system (hereafter, the ∆GO system), composed by YtkD, MutM and MutY. Furthermore, the simultaneous absence of Mfd and the GO system, (i) sensitized sporulating cells to H 2 O 2 , and (ii) elicited spontaneous and oxygen radical-induced rifampin-resistance (Rif r ) mutagenesis. Epifluorescence (EF), confocal and transmission electron (TEM) microscopy analyses, showed a decreased ability of ∆GO ∆ mfd strain to sporulate and to develop the typical morphologies of sporulating cells. Remarkably, disruption of sda , sirA and disA partially, restored the sporulation efficiency of the strain deficient for Mfd and the ∆GO system; complete restoration occurred in the RecA − background. Overall, our results unveil a novel Mfd mechanism of transcription-coupled-repair (TCR) elicited by 8-OxoG which converges in the activation of a RecA-dependent checkpoint event that control the onset of sporulation in B. subtilis .
其他摘要：Abstract During sporulation Bacillus subtilis Mfd couples transcription to nucleotide excision repair (NER) to eliminate DNA distorting lesions. Here, we report a significant decline in sporulation following Mfd disruption, which was manifested in the absence of external DNA-damage suggesting that spontaneous lesions activate the function of Mfd for an efficient sporogenesis. Accordingly, a dramatic decline in sporulation efficiency took place in a B. subtilis strain lacking Mfd and the repair/prevention guanine oxidized (GO) system (hereafter, the ∆GO system), composed by YtkD, MutM and MutY. Furthermore, the simultaneous absence of Mfd and the GO system, (i) sensitized sporulating cells to H 2 O 2 , and (ii) elicited spontaneous and oxygen radical-induced rifampin-resistance (Rif r ) mutagenesis. Epifluorescence (EF), confocal and transmission electron (TEM) microscopy analyses, showed a decreased ability of ∆GO ∆ mfd strain to sporulate and to develop the typical morphologies of sporulating cells. Remarkably, disruption of sda , sirA and disA partially, restored the sporulation efficiency of the strain deficient for Mfd and the ∆GO system; complete restoration occurred in the RecA − background. Overall, our results unveil a novel Mfd mechanism of transcription-coupled-repair (TCR) elicited by 8-OxoG which converges in the activation of a RecA-dependent checkpoint event that control the onset of sporulation in B. subtilis .
