Authors

J Black¹; S Virgilio¹; MS Bastos¹; J Damasceno²; G La Silva¹; K Crouch²; R McCulloch²; LR Tosi¹;  ¹ University of São Paulo Medical School, Brazil;  ² Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, UK

Discussion

Leishmania parasites collectively cause the neglected tropical infection Leishmaniasis. Leishmania have extremely plastic genomes which may promote adaptability in harsh environments and allow the rapid acquisition of drug resistance, but we understand little of how they co-ordinate these processes. Recently, proteins involved in tackling stress during DNA replication have been implicated as key plasticity factors, but little is known about the Leishmania replication stress response (RSR). In most eukaryotes, exposed single-stranded DNA (ssDNA) accumulates at stalled or collapsed replication forks (i.e replication stress; RS), activating the RSR. The atypical kinase ATR is recruited and activated by the ssDNA binding tripartite complex RPA (RPA1-RPA2-RPA3) and the heterotrimeric complex, 9-1-1 (RAD9-RAD1-HUS1). Activated ATR then aids repair factor co-ordination promotes cell cycle stalling, DNA replication fork protection and DNA repair. Here, we examined the distribution of three core RSR factors, H2A (a marker of DNA damage), LmRPA1 (RPA complex) and LmHUS1 (9-1-1 complex), throughout the Leishmania genome during a replication stress challenge by ChIP-seq. We show that known sites of variability are often marked by replication stress factors, which become enriched under replication stress. Many of these sites are also transcription hubs suggesting interactions between the processes of replication and transcription may drive plasticity. Furthermore, we show LmRPA1 mapping can be exploited to follow DNA replication under synchronising conditions.