Asymmetric dimeric assembly of Suv3 helicase facilitates processive RNA unwinding

Area of Science:

• Mitochondrial biology
• Molecular mechanisms of RNA processing
• Protein structure and function

Background:

• Human Suv3 is a dimeric helicase essential for mitochondrial RNA decay and surveillance.
• Its precise role in RNA unwinding has not been fully elucidated.
• Mitochondrial homeostasis relies on efficient RNA processing pathways.

Purpose of the Study:

• To elucidate the molecular mechanism of Suv3-mediated RNA unwinding.
• To determine the structural basis of Suv3's function in RNA decay.
• To investigate the role of Suv3 dimerization in its activity.

Main Methods:

• Near-atomic-resolution cryogenic electron microscopy (cryo-EM) to visualize Suv3 structures.
• Analysis of Suv3 in apo, ADP-bound, ssRNA-bound, and AMP-PNP-bound states.
• Biochemical assays to assess RNA-binding and unwinding efficiency.

Main Results:

• Revealed an unexpected asymmetric dimeric organization of Suv3.
• Identified differential engagement of protomers in substrate binding.
• Demonstrated ATP-hydrolysis-dependent enhancement of RNA binding and unwinding by dimerization.

Conclusions:

• Suv3 functions through an asymmetric dimeric mechanism for processive RNA unwinding.
• Dimerization is critical for enhancing Suv3's RNA processing capabilities.
• Provides a mechanistic framework for Suv3's role in mitochondrial RNA surveillance.