期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2018
卷号：115
期号：28
页码：E6516-E6525
DOI：10.1073/pnas.1801101115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Evolutionary processes are driven by diverse molecular mechanisms that act in the creation and prevention of mutations. It remains unclear how these mechanisms are regulated because limitations of existing mutation assays have precluded measuring how mutation rates vary over time in single cells. Toward this goal, I detected nascent DNA mismatches as a proxy for mutagenesis and simultaneously followed gene expression dynamics in single Escherichia coli cells using microfluidics. This general microscopy-based approach revealed the real-time dynamics of mutagenesis in response to DNA alkylation damage and antibiotic treatments. It also enabled relating the creation of DNA mismatches to the chronology of the underlying molecular processes. By avoiding population averaging, I discovered cell-to-cell variation in mutagenesis that correlated with heterogeneity in the expression of alternative responses to DNA damage. Pulses of mutagenesis are shown to arise from transient DNA repair deficiency. Constitutive expression of DNA repair pathways and induction of damage tolerance by the SOS response compensate for delays in the activation of inducible DNA repair mechanisms, together providing robustness against the toxic and mutagenic effects of DNA alkylation damage.
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