Dissemin is shutting down on January 1st, 2025

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MDPI, International Journal of Molecular Sciences, 7(22), p. 3481, 2021

DOI: 10.3390/ijms22073481

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Investigation of the Interaction of Human Origin Recognition Complex Subunit 1 with G-Quadruplex DNAs of Human c-myc Promoter and Telomere Regions

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Postprint: archiving allowed
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Data provided by SHERPA/RoMEO

Abstract

Origin recognition complex (ORC) binds to replication origins in eukaryotic DNAs and plays an important role in replication. Although yeast ORC is known to sequence-specifically bind to a replication origin, how human ORC recognizes a replication origin remains unknown. Previous genome-wide studies revealed that guanine (G)-rich sequences, potentially forming G-quadruplex (G4) structures, are present in most replication origins in human cells. We previously suggested that the region comprising residues 413–511 of human ORC subunit 1, hORC1413–511, binds preferentially to G-rich DNAs, which form a G4 structure in the absence of hORC1413–511. Here, we investigated the interaction of hORC1413-511 with various G-rich DNAs derived from human c-myc promoter and telomere regions. Fluorescence anisotropy revealed that hORC1413–511 binds preferentially to DNAs that have G4 structures over ones having double-stranded structures. Importantly, circular dichroism (CD) and nuclear magnetic resonance (NMR) showed that those G-rich DNAs retain the G4 structures even after binding with hORC1413–511. NMR chemical shift perturbation analyses revealed that the external G-tetrad planes of the G4 structures are the primary binding sites for hORC1413–511. The present study suggests that human ORC1 may recognize replication origins through the G4 structure.