The mammalian pseudokinase SgK223, and its structurally related homologue SgK269, are oncogenic scaffolds that nucleate the assembly of specific signalling complexes and regulate tyrosine kinase signalling. Both SgK223 and SgK269 form homo- and hetero-oligomers, a mechanism that underpins a diversity of signalling outputs. However, mechanistic insights into SgK223 and SgK269 homo- and heterotypic association are lacking. Here we present the crystal structure of SgK223 pseudokinase domain and its adjacent N- and C-terminal helices. The structure reveals how the N- and C-regulatory helices engage in a novel fold to mediate the assembly of a high-affinity dimer. In addition, we identified regulatory interfaces on the pseudokinase domain required for the self-assembly of large open-ended oligomers. This study highlights the diversity in how the kinase fold mediates non-catalytic functions and provides mechanistic insights into how the assembly of these two oncogenic scaffolds is achieved in order to regulate signalling output.

Centrioles are characterized by a nine-fold arrangement of microtubule triplets held together by an inner protein scaffold. These structurally robust organelles experience strenuous cellular processes such as cell division or ciliary beating while performing their function. However, the molecular mechanisms underlying the stability of microtubule triplets, as well as centriole architectural integrity remain poorly understood. Here, using ultrastructure expansion microscopy for nanoscale protein mapping, we reveal that POC16 and its human homolog WDR90 are components of the microtubule wall along the central core region of the centriole. We further found that WDR90 is an evolutionary microtubule associated protein. Finally, we demonstrate that WDR90 depletion impairs the localization of inner scaffold components, leading to centriole structural abnormalities in human cells. Altogether, this work highlights that WDR90 is an evolutionary conserved molecular player participating in centriole architecture integrity.

NTNG2 encodes netrin-G2, a membrane-anchored protein implicated in the molecular organization of neuronal circuitry and synaptic organization and diversification in vertebrates. In this study, through a combination of exome sequencing and autozygosity mapping, we have identified 16 individuals (from seven unrelated families) with ultra-rare homozygous missense variants in NTNG2; these individuals present with shared features of a neurodevelopmental disorder consisting of global developmental delay, severe to profound intellectual disability, muscle weakness and abnormal tone, autistic features, behavioral abnormalities, and variable dysmorphisms. The variants disrupt highly conserved residues across the protein. Functional experiments, including in silico analysis of the protein structure, in vitro assessment of cell surface expression, and in vitro knockdown, revealed potential mechanisms of pathogenicity of the variants, including loss of protein function and decreased neurite outgrowth. Our data indicate that appropriate expression of NTNG2 plays an important role in neurotypical development.

27Centrioles are characterized by a nine-fold arrangement of long-lived 28 microtubule triplets that are held together by an inner protein scaffold. These 29 structurally robust organelles experience strenuous cellular processes such as cell 30 division or ciliary beating while performing their function. However, the molecular 31 mechanisms underlying the stability of microtubule triplets, as well as centriole 32 architectural integrity remain poorly understood. Here, using ultrastructure expansion 33 microscopy (U-ExM) for nanoscale protein mapping, we reveal that POC16 and its 34 human homolog WDR90 are components of the centriolar microtubule wall along the 35 central core region of the centriole. We further found that WDR90 is an evolutionary 36 microtubule associated protein with a predicted structurally homology with the ciliary 37 inner junction protein FAP20. Finally, we demonstrate that WDR90 depletion impairs 38 the localization of inner scaffold components, leading to centriole structural 39 abnormalities in both human and Chlamydomonas cells. Altogether, this work 40 highlights that POC16/WDR90 is a crucial evolutionary conserved molecular player 41 participating in centriole architecture integrity. 42 43 44 45