Vms1p is a release factor for the ribosome-associated quality control complex.

Area of Science:

• Cellular Biology
• Molecular Biology
• Protein Homeostasis

Background:

• Eukaryotic cells possess the ribosome-associated quality control complex (RQC) to manage homeostasis when ribosomes stall.
• The RQC includes Ltn1p, Cdc48p, Rqc1p, and Rqc2p, and acts on stalled 60S ribosomal subunits bound to peptidyl-tRNA.
• Ribosome stalling can lead to the accumulation of potentially toxic protein aggregates if not resolved.

Purpose of the Study:

• To identify novel factors involved in the ribosome-associated quality control (RQC) pathway.
• To elucidate the mechanism by which stalled polypeptides are released from the RQC.
• To understand the role of Vms1p in resolving ribosome stalling and preventing protein aggregation.

Main Methods:

• Biochemical assays to study RQC complex assembly and function.
• In vitro reconstitution experiments with purified RQC components and Vms1p.
• Analysis of nascent chain processing and ubiquitination in yeast mutants.

Main Results:

• Vms1p functions as a tRNA hydrolase, specifically releasing stalled polypeptides engaged by the RQC.
• Vms1p acts on the 60S:peptidyl-tRNA complex, facilitating the release of incomplete nascent chains.
• This release mechanism by Vms1p is crucial for preventing the aggregation of CAT-tailed nascent chains.

Conclusions:

• Vms1p is a key component of the RQC pathway, acting as a tRNA hydrolase.
• Vms1p's activity is essential for the efficient clearance of stalled polypeptides.
• The identification of Vms1p provides new insights into cellular quality control mechanisms and protein homeostasis.