Substrate binding allosterically relieves autoinhibition of the TRIB1 pseudokinase

Abstract

Abstract:The Tribbles family of pseudokinases recruit substrates to the COP1 ubiquitin ligase for ubiquitination. CCAAT-enhancer binding protein (C/EBP) family transcription factors are crucial Tribbles substrates in adipocyte and myeloid development. Here we show that the TRIB1 pseudokinase can recruit various C/EBP family members, with binding of C/EBPβ attenuated by phosphorylation. To explain the mechanism of substrate recruitment, we solved the crystal structure of TRIB1 in complex with C/EBPα. TRIB1 undergoes a significant conformational change relative to its substrate-free structure, to bind C/EBPα in a pseudo-substrate-like manner.Crucially, substrate binding triggers allosteric changes that link substrate recruitment to COP1 binding, which is consistent with molecular dynamics and biochemical studies. These findings offer a view of pseudokinase regulation with striking parallels to bona fide kinase regulationvia the activation loop and αC-helix-and raise the possibility of small molecules targeting either the activation loop-in, or loop-out, conformations of Tribbles pseudokinases.All rights reserved. No reuse allowed without permission.was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.

New insights into the evolutionary conservation of the sole PIKK pseudokinase Tra1/TRRAP

“…Although many studies confirmed the importance of protein-protein interaction in Tra1/TRRAP function, mutational analyses of S. cerevisiae Tra1 indicated that its pseudokinase domain has also critical roles in vivo [25][26][27]. Similarly, recent work established that the atypical sequence of the TRIB pseudokinase domain relates to an important functional fold, whose plasticity modulates substrate ubiquitination or assembly of signaling modules [28][29][30].…”

Genomic mapping of copy number variations influencing immune response in breast cancer

“…This has been observed with mutations, where a compound was able to compete with the ATP or induce an allosteric change of the kinase pocket (7,8). Many examples have been described in different solid tumors, and many of these therapies have reached the clinical setting (9)(10)(11)(12)(13)(14)(15)(16)). Similar findings have been observed with the amplification of genes that code for proteins with a relevant role in cell signaling, like HER2 in BC (17,18).…”