Human Origin Recognition Complex Binds Preferentially to G-quadruplex-preferable RNA and Single-stranded DNA

Abstract

Background: ORC binds to replication origins, but human ORC does not exhibit apparent sequence-specificity. Results: G-quadruplex (G4)-preferable RNA or single-stranded DNA competes for DNA binding of ORC. Conclusion: Human ORC binds preferentially to RNA and single-stranded DNA that form G4, and the certain domain in ORC1 is involved in this binding. Significance: This ability may correlate with the G4-formable motif in human replication origins.

Characterizing and controlling intrinsic biases of lambda exonuclease in nascent strand sequencing reveals phasing between nucleosomes and G-quadruplex motifs around a subset of human replication origins

“…Mutagenesis studies (Valton et al 2014) will have to discern if early activation of origins in S phase is just a secondary effect of G4s influencing transcription and opening chromatin structure. ORC preferentially binds to G4s in single-stranded DNA and RNA in vitro (Hoshina et al 2013), suggesting that ORC might bind G4s in vivo. However, G4 binding of ORC was based on gel shift competition and was comparable to AT-rich dsDNA as a competitor.…”

Nonreplicative functions of the origin recognition complex

“…Although further research is required to determine the role of the ORC-RNA interaction in various biological processes, this data is very interesting and extends dramatically our understanding of ORC functions. Interestingly, it has recently been shown that human ORC has a much higher affinity to RNA than to either the double-stranded or single-strainded DNA in vitro [109], which encourages further investigation of RNA-ORC interactions in vivo .…”

Comment l’approche génomique aide à comprendre le processus d’initiation de la réplication

“…Le modèle le plus probable est que dans un environnement chromatinien ouvert, le complexe ORC reconnaît aspé-cifiquement une séquence ADN. Cette interprétation est cohérente avec les données biochimiques qui ont été accumulées depuis de nombreuses années indiquant que le complexe ORC lie l'ADN indépendamment de sa séquence [1,2,37]. Ces observations suggèrent donc que le complexe ORC se lierait à la chromatine de manière opportuniste au niveau de régions de chromatine ouverte [10,38].…”

“…Une information de structure de l'ADN, plutôt que de séquence, permettrait donc le recrutement du complexe ORC et l'établissement des origines. Toutefois, des approches de biochimie n'ont pas permis de mettre en évidence une affinité de ORC avec des structures de ce type in vitro ( [37] …”