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Updated: May 23, 2026

Inducing a Site Specific Replication Blockage in E. coli Using a Fluorescent Repressor Operator System
Published on: August 21, 2016
Modulation of the Pyrococcus abyssi NucS endonuclease activity by replication clamp at functional and structural
Christophe Creze1, Alessio Ligabue, Sébastien Laurent
1Ifremer, UMR6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France.
Abstract:
Pyrococcus abyssi NucS is the founding member of a new family of structure-specific DNA endonucleases that interact with the replication clamp proliferating cell nuclear antigen (PCNA). Using a combination of small angle x-ray scattering and surface plasmon resonance analyses, we demonstrate the formation of a stable complex in solution, in which one molecule of the PabNucS homodimer binds to the outside surface of the PabPCNA homotrimer. Using fluorescent labels, PCNA is shown to increase the binding affinity of NucS toward single-strand/double-strand junctions on 5' and 3' flaps, as well as to modulate the cleavage specificity on the branched DNA structures. Our results indicate that the presence of a single major contact between the PabNucS and PabPCNA proteins, together with the complex-induced DNA bending, facilitate conformational flexibility required for specific cleavage at the single-strand/double-strand DNA junction.
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