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Genome-wide mapping reveals R-loops associated with centromeric repeats in maize

R-loops are stable chromatin structures comprising a DNA:RNA hybrid and a displaced single-stranded DNA. R-loops have been implicated in gene expression and chromatin structure, as well as in replication blocks and genome instability. Here, we conducted a genome-wide identification of R-loops and id...

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Detalles Bibliográficos
Autores principales: Liu, Yang, Liu, Qian, Su, Handong, Liu, Kunpeng, Xiao, Xue, Li, Wei, Sun, Qianwen, Birchler, James A., Han, Fangpu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Cold Spring Harbor Laboratory Press 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8327920/
https://www.ncbi.nlm.nih.gov/pubmed/34244230
http://dx.doi.org/10.1101/gr.275270.121
Descripción
Sumario:R-loops are stable chromatin structures comprising a DNA:RNA hybrid and a displaced single-stranded DNA. R-loops have been implicated in gene expression and chromatin structure, as well as in replication blocks and genome instability. Here, we conducted a genome-wide identification of R-loops and identified more than 700,000 R-loop peaks in the maize (Zea mays) genome. We found that sense R-loops were mainly enriched in promoters and transcription termination sites and relatively less enriched in gene bodies, which is different from the main gene-body localization of sense R-loops in Arabidopsis and Oryza sativa. At the chromosome scale, maize R-loops were enriched in pericentromeric heterochromatin regions, and a significant portion of R-loops were derived from transposable elements. In centromeres, R-loops preferentially formed within the binding regions of the centromere-specific histone CENH3, and centromeric retrotransposons were strongly associated with R-loop formation. Furthermore, centromeric retrotransposon R-loops were observed by applying the single-molecule imaging technique of atomic force microscopy. These findings elucidate the fundamental character of R-loops in the maize genome and reveal the potential role of R-loops in centromeres.