Structural Insights into Pseudokinase Domains of Receptor Tyrosine Kinases

Abstract

Despite their apparent lack of catalytic activity, pseudokinases are essential signaling molecules.Here, we describe the structural and dynamic properties of pseudokinase domains from the Wntbinding receptor tyrosine kinases (PTK7, ROR1, ROR2, RYK), which play important roles in development. We determined structures of all pseudokinase domains in this family, and found that they share a conserved inactive conformation in their activation loop that resembles the autoinhibited insulin receptor kinase (IRK). They also have inaccessible ATP binding pockets, occluded by aromatic residues that mimic a cofactor-bound state. Structural comparisons revealed significant domain plasticity, and alternative interactions that substitute for absent conserved motifs. The pseudokinases also showed strikingly similar dynamic properties to IRK.Despite the inaccessible ATP site, screening identified ATP competitive type-II inhibitors for ROR1. Our results set the stage for an emerging therapeutic modality of "conformational disruptors" to inhibit or modulate non-catalytic functions of pseudokinases deregulated in disease.

The WNT/ROR Pathway in Cancer: From Signaling to Therapeutic Intervention

“…While the kinase function of the RORs has been a point of discussion [ 17 , 19 , 141 ], several other kinases have been implicated in their phosphorylation, and thus activation. Examples include GSK3, the receptor tyrosine kinase MET or the proto-oncogene SRC [ 16 , 17 , 75 , 130 , 142 ].…”

Dimeric Structure of the Pseudokinase IRAK3 Suggests an Allosteric Mechanism for Negative Regulation

“…Such inhibitors could either stabilize the closed conformation or destabilize it to affect the downstream signaling events that IRAK3 regulates. A similar approach has been established for small molecules that disrupt the conformation of the pseudokinase ROR1 ( Sheetz et al., 2020 ). Alternatively, inhibitors could be used to develop PROTACs for targeted degradation, as has been demonstrated recently ( Degorce et al., 2020 ).…”

Heterozygous Recurrent Mutations Inducing Dysfunction of ROR2 Gene in Patients With Short Stature

“…Also, several studies suggested that both ROR1 and ROR2 might be pseudokinases (Gentile et al, 2011;Debebe and Rathmell, 2015). However, recent studies by Nevenzal et al (2019) and Sheetz et al (2020) had found the autophosphorylation activity and autoinhibitory interactions of the TKD in the ROR2 protein from the perspective of highthroughput phosphorylation detection and protein structure. Consistent with results from experiments in vitro, five of our patients carrying the c.1675G > A heterozygous mutation mainly displayed short stature.…”