Proteomic analysis of yeast mutant RNA exosome complexes

Area of Science:

• Molecular Biology
• Biochemistry
• Yeast Genetics

Background:

• The yeast exosome is a crucial multiprotein complex responsible for RNA processing and degradation.
• It comprises a nine-subunit core associated with two 3'-5' exoribonucleases, and its assembly is vital for function.
• Mutations in core subunits, like Rrp43p, can impair exosome activity.

Purpose of the Study:

• To investigate the impact of Rrp43p mutations on yeast exosome complex stability and activity.
• To understand how Rrp43p mutations affect exosome subunit interactions and overall function.

Main Methods:

• Purification of Rrp43p and its mutant forms using the TAP method.
• Mass spectrometry to analyze copurified exosome subunits and protein interactions.
• Assessment of exosome activity and complex stability.

Main Results:

• Mutant Rrp43p proteins copurified with lower amounts of exosome subunits, indicating decreased complex stability.
• The exosome complex showed increased non-specific protein interactions when associated with mutant Rrp43p.
• Mutant exosome complexes exhibited enhanced exonuclease activity, suggesting altered dissociation constants.

Conclusions:

• Complexes containing mutant Rrp43p are less stable and display altered activity.
• Rrp43p mutations influence exosome stability, subunit association, and catalytic function.
• The findings provide insights into the structural and functional roles of Rrp43p within the yeast exosome.