Replisome bypass of transcription complexes and R-loops. Issue 18 (14th September 2020)

• Record Type: Journal Article
• Authors: Brüning, Jan-Gert; Marians, Kenneth J
• Is Part Of: Nucleic acids research. Volume 48:Issue 18(2020)
• Page Start: 10353
• Page End: 10367
• Publication Date: 2020-09-14
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkaa741
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: The vast majority of the genome is transcribed by RNA polymerases. G+C-rich regions of the chromosomes and negative superhelicity can promote the invasion of the DNA by RNA to form R-loops, which have been shown to block DNA replication and promote genome instability. However, it is unclear whether the R-loops themselves are sufficient to cause this instability or if additional factors are required. We have investigated replisome collisions with transcription complexes and R-loops using a reconstituted bacterial DNA replication system. RNA polymerase transcription complexes co-directionally oriented with the replication fork were transient blockages, whereas those oriented head-on were severe, stable blockages. On the other hand, replisomes easily bypassed R-loops on either template strand. Replication encounters with R-loops on the leading-strand template (co-directional) resulted in gaps in the nascent leading strand, whereas lagging-strand template R-loops (head-on) had little impact on replication fork progression. We conclude that whereas R-loops alone can act as transient replication blocks, most genome-destabilizing replication fork stalling likely occurs because of proteins bound to the R-loops.