TY - JOUR TI - Engineered proteins detect spontaneous DNA breakage in human and bacterial cells AU - Shee, Chandan AU - Cox, Ben D AU - Gu, Franklin AU - Luengas, Elizabeth M AU - Joshi, Mohan C AU - Chiu, Li-Ya AU - Magnan, David AU - Halliday, Jennifer A AU - Frisch, Ryan L AU - Gibson, Janet L AU - Nehring, Ralf Bernd AU - Do, Huong G AU - Hernandez, Marcos AU - Li, Lei AU - Herman, Christophe AU - Hastings, PJ AU - Bates, David AU - Harris, Reuben S AU - Miller, Kyle M AU - Rosenberg, Susan M A2 - Walter, Johannes VL - 2 PY - 2013 DA - 2013/10/29 SP - e01222 C1 - eLife 2013;2:e01222 DO - 10.7554/eLife.01222 UR - https://doi.org/10.7554/eLife.01222 AB - Spontaneous DNA breaks instigate genomic changes that fuel cancer and evolution, yet direct quantification of double-strand breaks (DSBs) has been limited. Predominant sources of spontaneous DSBs remain elusive. We report synthetic technology for quantifying DSBs using fluorescent-protein fusions of double-strand DNA end-binding protein, Gam of bacteriophage Mu. In Escherichia coli GamGFP forms foci at chromosomal DSBs and pinpoints their subgenomic locations. Spontaneous DSBs occur mostly one per cell, and correspond with generations, supporting replicative models for spontaneous breakage, and providing the first true breakage rates. In mammalian cells GamGFP—labels laser-induced DSBs antagonized by end-binding protein Ku; co-localizes incompletely with DSB marker 53BP1 suggesting superior DSB-specificity; blocks resection; and demonstrates DNA breakage via APOBEC3A cytosine deaminase. We demonstrate directly that some spontaneous DSBs occur outside of S phase. The data illuminate spontaneous DNA breakage in E. coli and human cells and illustrate the versatility of fluorescent-Gam for interrogation of DSBs in living cells. KW - DNA double-strand break KW - endogenous DNA damage KW - GFP KW - fluorescent-protein fusion KW - spontaneous DNA break KW - synthetic biology JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -