Abstact

The E3 ligase betaTrCP regulates a significant number of important cytosolic proteins by recognizing and binding to a "DSGXXS" consensus phosphodegron sequence, resulting in the ubiquitination and degradation of target proteins. While many of the substrates of betaTrCP have strong disease links, there is high-resolution structural data available for just one of these proteins in complex with betaTrCP. Here, we describe the development of a robust crystallographic system for betaTrCP and report high-resolution crystal structures for betaTrCP in complex with degrons from five new targets, encompassing the important cancer proteins, WEE1, claspin, ATF4, PDCD4, and IkappaBalpha. Interestingly, these structures reveal the molecular basis by which betaTrCP can recognize and bind both consensus and nonconsensus degron peptides and reveal an overall general plasticity in degron binding mode. We also provide a biochemical assessment of the binding affinities of these peptides for betaTrCP, adding further insight into the molecular interactions observed in the crystal structures. Finally, computational analyses of the betaTrCP complexes identify opportunities for potential molecular glue approaches.