New interacting partners of the F-box protein Ufo1 of yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• The F-box protein Ufo1 in yeast is involved in genome stability and recruits substrates for ubiquitylation by the SCF ubiquitin ligase complex.
• Ufo1 possesses three ubiquitin interacting motifs (UIMs), and its deletion is lethal, while its truncated form arrests the cell cycle.
• Previous studies failed to identify Ufo1-interacting proteins using C-terminal tagging.

Purpose of the Study:

• To identify Ufo1-interacting proteins using a stabilized N-terminally tagged Ufo1 mutant lacking UIMs (Ufo1 Delta UIM).
• To elucidate the role of UIMs in Ufo1 ubiquitylation and its interaction with the proteasome.
• To expand the understanding of the Ufo1 protein network and its function in cell cycle regulation.

Main Methods:

• Utilized mass spectrometry to identify proteins interacting with N-terminally tagged Ufo1 Delta UIM.
• Employed yeast genetics and protein biochemistry techniques.
• Investigated Ufo1 ubiquitylation in vivo.

Main Results:

• Identified novel Ufo1-interacting proteins involved in transcription.
• Confirmed an indirect interaction with Hsp70 molecular chaperones via the Skp1 adaptor.
• Demonstrated a direct interaction between Ufo1 and the 19S regulatory particle of the proteasome.
• Showed that UIMs are essential for Ufo1 ubiquitylation in vivo.

Conclusions:

• The UIMs of Ufo1 are critical for its ubiquitylation, facilitating the turnover of SCF Ufo1 complexes.
• This turnover allows for the recycling of SCF complex core subunits, promoting cell cycle progression.
• The findings expand the known interactome of Ufo1 and highlight the importance of its UIMs in regulating protein stability and cell cycle.