Connecting the dots: RPA and R-loops in trypanosomatids

• Grant number: 25/19954-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: January 26, 2026
• End date: January 25, 2027
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Maria Carolina Quartim Barbosa Elias Sabbaga
• Grantee: Giovanna Nalin Parmegiani
• Supervisor: Richard Mcculloch
• Host Institution: Instituto Butantan. São Paulo , SP, Brazil
• Institution abroad: University of Glasgow, Scotland
• Associated to the scholarship: 21/12872-9 - Investigation of the mechanism of nucleus-cytoplasm RPA transport, BP.DD

Abstract

Kinetoplastid parasites such as Trypanosoma cruzi and Trypanosoma brucei alternate between insect vectors and mammalian hosts, facing contrasting environments and intense immune pressure. Thriving under such conditions requires generating genetic diversity while preserving core functions. In T. cruzi, our group has been studying the involvement of replication-transcription collisions in genetic variability. In many organisms, including trypanosomatids, such conflicts are often linked to DNA:RNA hybrids (R-loops), which have key regulatory roles but, when accumulated, cause replication stress and DNA damage. The Replication Protein A (RPA) complex, a central single-stranded DNA-binding factor, is essential for replication and repair and also contributes to R-loop regulation in model systems; this connection, however, remains unexplored in trypanosomatids. Preliminary data from my PhD indicate that, in T. cruzi, RPA subunits localize to R-loop-rich nuclear regions and interact with ALBA-family proteins, known R-loop binders, and ribosomal proteins, suggesting recruitment to the nucleolus, a major R-loop hotspot. Moreover, our group identified a putative novel RPA subunit (named RPA-like) in T. brucei and found its expression also in T. cruzi, supporting, together with evidence from other organisms, that the RPA complex may be more structurally diverse than previously recognized. This project will combine genomic mapping, chromatin immunoprecipitation, proteomics, and CRISPR-Cas9-based tagging to investigate RPA-R-loop interactions and the role of RPA-like in trypanosomatids, building on the host laboratory's expertise to advance understanding of genome maintenance versus variability in these parasites.