Single-stranded DNA-binding protein hSSB1 is critical for genomic stability.

Single-strand DNA (ssDNA)-binding proteins (SSBs) are ubiquitous and essential for a wide variety of DNA metabolic processes, including DNA replication, recombination, DNA damage detection and repair. SSBs have multiple roles in binding and sequestering ssDNA, detecting DNA damage, stimulating nucleases, helicases and strand-exchange proteins, activating transcription and mediating protein-protein interactions. In eukaryotes, the major SSB, replication protein A (RPA), is a heterotrimer.

Insights into ssDNA recognition by the OB fold from a structural and thermodynamic study of Sulfolobus SSB protein.

Information processing pathways such as DNA replication are conserved in eukaryotes and archaea and are significantly different from those found in bacteria. Single-stranded DNA-binding (SSB) proteins (or replication protein A, RPA, in eukaryotes) play a central role in many of these pathways. However, whilst euryarchaea have a eukaryotic-type RPA homologue, crenarchaeal SSB proteins appear much more similar to the bacterial proteins, with a single OB fold for DNA binding and a flexible C-terminal tail that is implicated in protein-protein interactions.