Non-B DNA Secondary Structures and Their Resolution by RecQ Helicases

Abstract EN

In addition to the canonical B-form structure first described by Watson and Crick, DNA can adopt a number of alternative structures.

These non-B-form DNA secondary structures form spontaneously on tracts of repeat sequences that are abundant in genomes.

In addition, structured forms of DNA with intrastrand pairing may arise on single-stranded DNA produced transiently during various cellular processes.

Such secondary structures have a range of biological functions but also induce genetic instability.

Increasing evidence suggests that genomic instabilities induced by non-B DNA secondary structures result in predisposition to diseases.

Secondary DNA structures also represent a new class of molecular targets for DNA-interactive compounds that might be useful for targeting telomeres and transcriptional control.

The equilibrium between the duplex DNA and formation of multistranded non-B-form structures is partly dependent upon the helicases that unwind (resolve) these alternate DNA structures.

With special focus on tetraplex, triplex, and cruciform, this paper summarizes the incidence of non-B DNA structures and their association with genomic instability and emphasizes the roles of RecQ-like DNA helicases in genome maintenance by resolution of DNA secondary structures.

In future, RecQ helicases are anticipated to be additional molecular targets for cancer chemotherapeutics.