Comparison of Cross-Regulation by Different OTUB1:E2 Complexes

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• OTUB1 is a cysteine protease that cleaves K48-linked polyubiquitin chains.
• OTUB1 interacts with E2 ubiquitin conjugating enzymes, modulating their activities.
• The interplay between OTUB1 and E2 enzymes is crucial for ubiquitin signaling.

Purpose of the Study:

• To investigate the kinetics and thermodynamics of OTUB1:E2 complexes.
• To understand the balance between OTUB1's inhibitory and stimulatory effects on E2 enzymes.
• To explore the physiological relevance of OTUB1-E2 interactions.

Main Methods:

• Characterization of OTUB1:E2 complex formation and activity.
• Kinetic and thermodynamic analyses.
• Enzyme assays using various E2 enzyme isoforms.

Main Results:

• OTUB1 noncatalytically inhibits E2 ubiquitin conjugating activity.
• E2 enzymes stimulate OTUB1 deubiquitinating activity at physiologically relevant concentrations.
• OTUB1 inhibits UBE2E1, UBE2E2, and UBE2E3 enzymes, and their autoubiquitination, except for UBE2E3.

Conclusions:

• OTUB1 and E2 enzyme interactions are complex, involving both inhibition and stimulation.
• These interactions occur at concentrations relevant to cellular environments.
• Quantitative insights into OTUB1:E2 complexes pave the way for understanding their biological roles.