Ubiquitin Substrates Dramatically Increase Ataxin3 Deubiquitinating Activity: Allosteric crosstalk connects three distinct sites

Abstract

Ubiquitin signaling networks modulate almost all aspects of eukaryotic biology, and their outputs reflect the dynamic balance between ubiquitin attachment and removal. The latter process is catalyzed by deubiquitinating enzymes (DUBs), which must be carefully regulated to ensure that their activities are applied appropriately. Ataxin3 is a DUB that participates in quality-control pathways that support cellular health; however, the regulation of its activity has remained poorly understood. Here, we show that ataxin3 can be dramatically activated by naturally occurring ubiquitin species, and that this activation involves a previously uncharacterized interplay between three distinct sites on the enzyme. Our improved understanding of ataxin3 regulation provides insights into allosteric mechanisms that may prove applicable to other enzymes in the ubiquitin universe.