Characterization of the Structural and Protein Recognition Properties of Hybrid PNA-DNA Four-Way Junctions

Document Type

Article

Publication Date

12-1-2015

Department

Chemistry and Biochemistry

School

Mathematics and Natural Sciences

Abstract

The objective of this study is to evaluate the structure and protein recognition properties of hybrid four-way junctions (4WJs) composed of DNA and peptide nucleic acid (PNA) strands. We compare a classic immobile DNA junction, J1, vs. six PNA–DNA junctions, including a number with blunt DNA ends and multiple PNA strands. Circular dichroism (CD) analysis reveals that hybrid 4WJs are composed of helices that possess structures intermediate between A- and B-form DNA, the apparent level of A-form structure correlates with the PNA content. The structure of hybrids that contain one PNA strand is sensitive to Mg+2. For these constructs, the apparent B-form structure and conformational stability (Tm) increase in high Mg+2. The blunt-ended junction, b4WJ-PNA3, possesses the highest B-form CD signals and Tm (40.1 °C) values vs. all hybrids and J1. Protein recognition studies are carried out using the recombinant DNA-binding protein, HMGB1b. HMGB1b binds the blunt ended single-PNA hybrids, b4WJ-PNA1 and b4WJ-PNA3, with high affinity. HMGB1b binds the multi-PNA hybrids, 4WJ-PNA1,3 and b4WJ-PNA1,3, but does not form stable protein-nucleic acid complexes. Protein interactions with hybrid 4WJs are influenced by the ratio of A- to B-form helices: hybrids with helices composed of higher levels of B-form structure preferentially associate with HMGB1b.

Comments

© This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/.

Publication Title

Archives of Biochemistry and Biophysics

Volume

587

First Page

1

Last Page

11

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