Structural components and architectures of RNA exosomes

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The RNA exosome is a crucial multi-subunit complex responsible for RNA processing and decay.
• Decades of research have focused on understanding the exosome's mechanisms, particularly its 3' to 5' exoribonucleolytic activity.

Purpose of the Study:

• To elucidate the structural organization of eukaryotic exosomes and their prokaryotic homologs (bacteria and archaea).
• To detail the mechanistic aspects of substrate recognition and RNA processing by these exosome complexes.
• To compare the distinct enzymatic activities (phosphorolytic, hydrolytic, endoribonucleolytic) across different domains of life.

Main Methods:

• Analysis of crystal structures of bacterial, archaeal, and eukaryotic exosome complexes and associated proteins.
• Comparative structural analysis to understand evolutionary relationships and functional divergence.

Main Results:

• Detailed structural insights into the eukaryotic RNA exosome and its sub-complexes.
• Structural characterization of bacterial (RNase PH, PNPase) and archaeal exosomes.
• Elucidation of structural basis for substrate recognition and diverse RNA processing activities.

Conclusions:

• Structural data provides a mechanistic understanding of RNA processing and decay by exosomes across life.
• Comparative analysis reveals conserved and divergent features in exosome structure and function.
• Key proteins like Rrp44 and Rrp6 play critical roles in eukaryotic RNA exosome activity.