Trypanosoma brucei ribonuclease H2A is an essential R-loop processing enzyme whose loss causes DNA damage during transcription initiation and antigenic variation

Briggs, E., Crouch, K. , Lemgruber Soares, L., Hamilton, G., Lapsley, C. and McCulloch, R. (2019) Trypanosoma brucei ribonuclease H2A is an essential R-loop processing enzyme whose loss causes DNA damage during transcription initiation and antigenic variation. Nucleic Acids Research, (doi:10.1093/nar/gkz644) (PMID:31350892) (Early Online Publication)

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Abstract

Ribonucleotides represent a threat to DNA genome stability and transmission. Two types of Ribonuclease H (RNase H) excise ribonucleotides when they form part of the DNA strand, or hydrolyse RNA when it base-pairs with DNA in structures termed R-loops. Loss of either RNase H is lethal in mammals, whereas yeast survives the absence of both enzymes. RNase H1 loss is tolerated by the parasite Trypanosoma brucei but no work has examined the function of RNase H2. Here we show that loss of T. brucei RNase H2 (TbRH2A) leads to growth and cell cycle arrest that is concomitant with accumulation of nuclear damage at sites of RNA polymerase (Pol) II transcription initiation, revealing a novel and critical role for RNase H2. Differential gene expression analysis reveals limited overall changes in RNA levels for RNA Pol II genes after TbRH2A loss, but increased perturbation of nucleotide metabolic genes. Finally, we show that TbRH2A loss causes R-loop and DNA damage accumulation in telomeric RNA Pol I transcription sites, also leading to altered gene expression. Thus, we demonstrate separation of function between two nuclear T. brucei RNase H enzymes during RNA Pol II transcription, but overlap in function during RNA Pol I-mediated gene expression during host immune evasion.

Item Type:Articles
Status:Early Online Publication
Refereed:Yes
Glasgow Author(s) Enlighten ID:Crouch, Dr Kathryn and Briggs, Miss Emma and Hamilton, Dr Graham and Lemgruber Soares, Dr Leandro and Lapsley, Mr Craig and McCulloch, Professor Richard
Authors: Briggs, E., Crouch, K., Lemgruber Soares, L., Hamilton, G., Lapsley, C., and McCulloch, R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Nucleic Acids Research
Publisher:Oxford University Press
ISSN:0305-1048
ISSN (Online):1362-4962
Published Online:27 July 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Nucleic Acids Research 2019
Publisher Policy:Reproduced under a Creative Commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
606431Kinase dependent control of DNA replication and repair as a drug target in Trypanosoma brucei.Richard McCullochBiotechnology and Biological Sciences Research Council (BBSRC)BB/K006495/1III - PARASITOLOGY
68706114CONFAP Understanding diverged genome repair and replication functions in trypanosomatid parasitesRichard McCullochBiotechnology and Biological Sciences Research Council (BBSRC)BB/M028909/1III - PARASITOLOGY
716221How do common and diverged features of the replicative stress response shape the biology of TriTrypRichard McCullochBiotechnology and Biological Sciences Research Council (BBSRC)BB/N016165/1III - PARASITOLOGY
698641Characterization of Toxoplasma gondii interaction with the human host cell and Host-Parasite co-evolution: Toxoplasma gondii as a case studyMusa HassanWellcome Trust (WELLCOTR)104111/B/14/ZIII - PARASITOLOGY