Binding dynamics of a monomeric SSB protein to DNA: a single-molecule multi-process approach

Michael John Morten, Jose Ramon Peregrina, Maria Figueira-Gonzalez, Katrin Ackermann, Bela Ernest Bode, Malcolm F White, Carlos Penedo

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
8 Downloads (Pure)

Abstract

Single-stranded DNA binding proteins (SSBs) are ubiquitous across all organisms and are characterized by the presence of an OB (oligonucleotide/oligosaccharide/oligopeptide) binding motif to recognize single-stranded DNA (ssDNA). Despite their critical role in genome maintenance, our knowledge about SSB function is limited to proteins containing multiple OB-domains and little is known about single OB-folds interacting with ssDNA. Sulfolobus solfataricus SSB (SsoSSB) contains a single OB-fold and being the simplest representative of the SSB-family may serve as a model to understand fundamental aspects of SSB:DNA interactions. Here, we introduce a novel approach based on the competition between Förster resonance energy transfer (FRET), protein-induced fluorescence enhancement (PIFE) and quenching to dissect SsoSSB binding dynamics at single monomer resolution. We demonstrate that SsoSSB follows a monomer-by-monomer binding mechanism that involves a positive-cooperativity component between adjacent monomers. We found that SsoSSB dynamic behaviour is closer to that of Replication Protein A than to Escherichia coli SSB; a feature that might be inherited from the structural analogies of their DNA-binding domains. We hypothesize that SsoSSB has developed a balance between highdensity binding and a highly dynamic interaction with ssDNA to ensure efficient protection of the genome but still allow access to ssDNA during vital cellular processes.
Original languageEnglish
Pages (from-to)10907-10924
Number of pages18
JournalNucleic Acids Research
Volume43
Issue number22
Early online date17 Nov 2015
DOIs
Publication statusPublished - 15 Dec 2015

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