An R-loop is a three-stranded nucleic acid structure, composed of a DNA:RNA hybrid and the associated non-template single-stranded DNA. R-loops may be formed in a variety of circumstances and may be tolerated or cleared by cellular components. The term "R-loop" was given to reflect the similarity of these structures to D-loops; the "R" in this case represents the involvement of an RNA moiety.
In the laboratory, R-loops can be created by transcription of DNA sequences (for example those that have a high GC content) that favor annealing of the RNA behind the progressing RNA polymerase.[1] At least 100bp of DNA:RNA hybrid is required to form a stable R-loop structure. R-loops may also be created by the hybridization of mature mRNA with double-stranded DNA under conditions favoring the formation of a DNA-RNA hybrid; in this case, the intron regions (which have been spliced out of the mRNA) form single-stranded DNA loops, as they cannot hybridize with complementary sequence in the mRNA.[2]
- ^ Hodson, Charlotte; van Twest, Sylvie; Dylewska, Malgorzata; O’Rourke, Julienne J.; Tan, Winnie; Murphy, Vincent J.; Walia, Mannu; Abbouche, Lara; Nieminuszczy, Jadwiga; Dunn, Elyse; Bythell-Douglas, Rohan; Heierhorst, Jörg; Niedzwiedz, Wojciech; Deans, Andrew J. (2022). "Branchpoint translocation by fork remodelers as a general mechanism of R-loop removal". Cell Reports. 41 (10): 111749. doi:10.1016/j.celrep.2022.111749.
- ^ Wang, Kang; Wang, Honghong; Li, Conghui; Yin, Zhinang; Xiao, Ruijing; Li, Qiuzi; Xiang, Ying; Wang, Wen; Huang, Jian; Chen, Liang; Fang, Pingping; Liang, Kaiwei (2021-02-19). "Genomic profiling of native R loops with a DNA-RNA hybrid recognition sensor". Science Advances. 7 (8). Bibcode:2021SciA....7.3516W. doi:10.1126/sciadv.abe3516. ISSN 2375-2548. PMC 7888926. PMID 33597247.