Dataset Information

Protein-Assisted Room-Temperature Assembly of Rigid, Immobile Holliday Junctions and Hierarchical DNA Nanostructures.

ABSTRACT: Immobile Holliday junctions represent not only the most fundamental building block of structural DNA nanotechnology but are also of tremendous importance for the in vitro investigation of genetic recombination and epigenetics. Here, we present a detailed study on the room-temperature assembly of immobile Holliday junctions with the help of the single-strand annealing protein Red?. Individual DNA single strands are initially coated with protein monomers and subsequently hybridized to form a rigid blunt-ended four-arm junction. We investigate the efficiency of this approach for different DNA/protein ratios, as well as for different DNA sequence lengths. Furthermore, we also evaluate the potential of Red? to anneal sticky-end modified Holliday junctions into hierarchical assemblies. We demonstrate the Red?-mediated annealing of Holliday junction dimers, multimers, and extended networks several microns in size. While these hybrid DNA-protein nanostructures may find applications in the crystallization of DNA-protein complexes, our work shows the great potential of Red? to aid in the synthesis of functional DNA nanostructures under mild reaction conditions.

SUBMITTER: Ramakrishnan S

PROVIDER: S-EPMC7663122 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Protein-Assisted Room-Temperature Assembly of Rigid, Immobile Holliday Junctions and Hierarchical DNA Nanostructures.

Ramakrishnan Saminathan S Subramaniam Sivaraman S Kielar Charlotte C Grundmeier Guido G Stewart A Francis AF Keller Adrian A

Molecules (Basel, Switzerland) 20201103 21

Immobile Holliday junctions represent not only the most fundamental building block of structural DNA nanotechnology but are also of tremendous importance for the in vitro investigation of genetic recombination and epigenetics. Here, we present a detailed study on the room-temperature assembly of immobile Holliday junctions with the help of the single-strand annealing protein Redβ. Individual DNA single strands are initially coated with protein monomers and subsequently hybridized to form a rigid ...[more]

PMID: 33153073

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Project description:Integration host factor (IHF) is a nucleoid-associated protein involved in DNA packaging, integration of viral DNA and recombination. IHF binds with nanomolar affinity to duplex DNA containing a 13 bp consensus sequence, inducing a bend of ~160° upon binding. We determined that IHF binds to DNA Four-way or Holliday junctions (HJ) with high affinity regardless of the presence of the consensus sequence, signifying a structure-based mechanism of recognition. Junctions, important intermediates in DNA repair and homologous recombination, are dynamic and can adopt either an open or stacked conformation, where the open conformation facilitates branch migration and strand exchange. Using ensemble and single molecule Förster resonance energy transfer (FRET) methods, we investigated IHF-induced changes in the population distribution of junction conformations and determined that IHF binding shifts the population to the open conformation. Further analysis of smFRET dynamics revealed that even in the presence of protein, the junctions remain dynamic as fast transitions are observed for the protein-bound open state. Protein binding alters junction conformational dynamics, as cross correlation analyses reveal the protein slows the transition rate at 1 mM Mg2+ but accelerates the transition rate at 10 mM Mg2+. Stopped flow kinetic experiments provide evidence for two binding steps, a rapid, initial binding step followed by a slower step potentially associated with a conformational change. These measurements also confirm that the protein remains bound to the junction during the conformer transitions and further suggest that the protein forms a partially dissociated state that allows junction arms to be dynamic. These findings, which demonstrate that IHF binds HJs with high affinity and stabilizes junctions in the open conformation, suggest that IHF may play multiple roles in the processes of integration and recombination in addition to stabilizing bacterial biofilms.

Dataset Information

Protein-Assisted Room-Temperature Assembly of Rigid, Immobile Holliday Junctions and Hierarchical DNA Nanostructures.

Publications

Protein-Assisted Room-Temperature Assembly of Rigid, Immobile Holliday Junctions and Hierarchical DNA Nanostructures.

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