Evolution and functional diversity of archaeal Replication Protein A

• Applicant: Dr. Anna Papageorgiou, Ph.D.
• Subject Area: Structural Biology ; Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577181617

Replication Protein A (RPA) is the primary single-stranded DNA-binding protein in Archaea and Eukaryotes; it is essential for genome integrity during DNA replication and repair. While canonical heterotrimeric RPAs are well-characterised, many Archaea encode atypical dimeric and/or monomeric variants whose structure and function remain largely unknown. This gap of knowledge limits our understanding of how essential protein complexes evolve and retain function despite architectural simplification. This project takes an integrative approach to uncover the functional and evolutionary diversity of archaeal RPAs. Using Methanosarcina acetivorans as a model system, I will combine biochemistry, biophysics, and structural biology to investigate how three distinct atypical RPA variants (two heterodimeric and a monomeric) bind and protect ssDNA. Preliminary results reveal major structural differences among the three RPA homologous variants, offering a unique opportunity to study François Jacob’s concept of ‘evolutionary tinkering’ within an essential genome maintenance complex. Building on these results, my project will pursue five specific objectives: i) Characterise the architectures, assembly, and oligomeric states of atypical RPAs in M. acetivorans; ii) Determine their ssDNA-binding properties and DNA-coating mechanisms; iii) Map the taxonomic distribution and structural diversity of RPA homologs across Archaea; iv) Reconstruct the evolutionary history of archaeal RPA, focusing on gene loss, domain reshuffling, and compensatory adaptations, and v) Examine potential interaction partners of non-canonical RPAs. By bridging structural and evolutionary biology, this project will reveal how genome stability is maintained in Archaea with simplified forms of an essential replication factor. My findings are expected to uncover unifying principles underlying the evolutionary origins of archaeal and eukaryotic replisomes. Moreover, this project will lay the foundation for my long-term research programme on the molecular evolution of the replisome, expanding to additional replication factors and the replisome as an integrated molecular machine. Support from this fellowship will be pivotal in establishing my independent research niche at the interface of molecular evolution and biochemistry and in building the expertise, visibility, and independence required to lead my own research group.

• DFG Programme: Position