Ye Qianying, Lee Chanjae, Shin Eunjung, Lee Sung-Jae
Department of Biology, Kyung Hee University, Seoul 02447, Korea.
Antioxidants (Basel). 2021 Oct 15;10(10):1623. doi: 10.3390/antiox10101623.
The transposition of insertion sequence elements was evaluated among different lineages, including the wild-type, a cystine importer-disrupted mutant, a complemented strain, and a cystine importer-overexpressed strain. Cellular growth reached early exponential growth at OD 2.0 and late exponential growth at OD 4.0. Exposing the cells to hydrogen peroxide (80-100 mM) resulted in the transposition of insertion sequences (ISs) in genes associated with the carotenoid biosynthesis pathway. Particularly, IS (an IS family member) and IS (an IS family member) from the cystine importer-disrupted mutant were transposed into phytoene desaturase (_0524) via replicative transposition. Further, the cystine importer-overexpressed strain Δ_1985R showed transposition of both IS and IS elements. In contrast, IS transposition was not detected in the complementary strain. Interestingly, a cystine importer-overexpressing strain exhibited streptomycin resistance, indicating that point mutation occurred in the (_1873) gene encoding ribosomal protein S12. qRT-PCR analyses were then conducted to evaluate the expression of oxidative stress response genes, IS elements, and low-molecular-weight thiol compounds such as mycothiol and bacillithiol. Nevertheless, the mechanisms that trigger IS transposition in redox imbalance conditions remain unclear. Here, we report that the active transposition of different IS elements was affected by intracellular redox imbalances caused by cystine importer deficiencies or overexpression.
在不同谱系中评估了插入序列元件的转座情况，包括野生型、胱氨酸转运体破坏突变体、互补菌株和胱氨酸转运体过表达菌株。细胞生长在OD 2.0时达到早期指数生长期，在OD 4.0时达到晚期指数生长期。将细胞暴露于过氧化氢（80 - 100 mM）会导致与类胡萝卜素生物合成途径相关基因中的插入序列（IS）发生转座。特别地，来自胱氨酸转运体破坏突变体的IS（一个IS家族成员）和IS（一个IS家族成员）通过复制转座被转座到八氢番茄红素去饱和酶（_0524）中。此外，胱氨酸转运体过表达菌株Δ_1985R显示出IS和IS元件的转座。相比之下，在互补菌株中未检测到IS转座。有趣的是，一个胱氨酸转运体过表达菌株表现出链霉素抗性，表明在编码核糖体蛋白S12的（_1873）基因中发生了点突变。然后进行了qRT-PCR分析以评估氧化应激反应基因、IS元件以及低分子量硫醇化合物如麦角硫因和杆菌硫醇的表达。然而，在氧化还原失衡条件下触发IS转座的机制仍不清楚。在此，我们报告不同IS元件的活性转座受到胱氨酸转运体缺陷或过表达引起的细胞内氧化还原失衡的影响。
