An optimised system for rapid auxin-inducible protein degradation in budding yeast

The auxin system for inducible protein degradation is a powerful tool to investigate protein function. It consists of a degron fused to a target protein, an auxin-related ligand that binds to the degron, and a receptor that recognises the auxin-bound degron and mediates proteasomal degradation of the target protein. Variants of all system components are available, and we here test three degrons, three auxins and three degron receptors to identify optimal combinations of these variants in budding yeast. We show that the degrons mIAA7 or AID* together with adamantyl-auxin and the degron receptor OsTIR1(F74G) allow particularly rapid and extensive degradation. Basal degradation in the absence of auxin is generally low and can be prevented entirely by inducible expression of OsTIR1(F74G). Finally, we demonstrate that the remarkable efficiency of this system makes it competitive with established chemical inhibitors, such as tunicamycin and MG132, and with temperature-sensitive mutant alleles. These findings will aid the effective application of the auxin system.