Ribonuclease H1-targeted R-loops in surface antigen gene expression sites can direct trypanosome immune evasion

Emma Briggs, Kathryn Crouch, Leandro Lemgruber, Craig Lapsley, Richard McCulloch

Research output: Contribution to journalArticlepeer-review

Abstract

Switching of the Variant Surface Glycoprotein (VSG) in Trypanosoma brucei provides a crucial host immune evasion strategy that is catalysed both by transcription and recombination reactions, each operating within specialised telomeric VSG expression sites (ES). VSG switching is likely triggered by events focused on the single actively transcribed ES, from a repertoire of around 15, but the nature of such events is unclear. Here we show that RNADNA hybrids, called R-loops, form preferentially within sequences termed the 70 bp repeats in the actively transcribed ES, but spread throughout the active and inactive ES, in the absence of RNase H1, which degrades R-loops. Loss of RNase H1 also leads to increased levels of VSG coat switching and replication-associated genome damage, some of which accumulates within the active ES. This work indicates VSG ES architecture elicits R-loop formation, and that these RNA-DNA hybrids connect T. brucei immune evasion by transcription and recombination.
Original languageEnglish
Article numbere1007729
Number of pages25
JournalPLoS Genetics
Volume14
Issue number2
DOIs
Publication statusPublished - 13 Dec 2018

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