Action and function of helicases on RNA G-quadruplexes

The nucleic acid structure called G-quadruplex (G4) is currently discussed to function in nucleic acid-based mechanisms that influence several cellular processes. They can modulate the cellular machinery either positively or negatively, both at the DNA and RNA level. The majority of what we know about G4 biology comes from DNA G4 (dG4) research. RNA G4s (rG4), on the other hand, are gaining interest as researchers become more aware of their role in several aspects of cellular homeostasis. In either case, the correct regulation of G4 structures within cells is essential and demands specialized proteins able to resolve them. Small changes in the formation and unfolding of G4 structures can have severe consequences for the cells that could even stimulate genome instability, apoptosis or proliferation. Helicases are the most relevant negative G4 regulators, which prevent and unfold G4 formation within cells during different pathways. Yet, and despite their importance only a handful of rG4 unwinding helicases have been identified and characterized thus far. This review addresses the current knowledge on rG4s-processing helicases with a focus on methodological approaches. An example of a non-helicase rG4s-unwinding protein is also briefly described.

Automated summary

The nucleic acid structure known as G-quadruplex (G4) plays a significant role in nucleic acid-based mechanisms that impact cellular processes. DNA G4 is well-studied, while RNA G4 is gaining attention for its role in cellular homeostasis. Proper regulation of G4 structures within cells is crucial, and helicases are important in resolving them. However, only a few rG4 unwinding helicases have been identified and characterized so far.