bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.04.29.489987

Nanobodies identify an activated state of the TRIB2 pseudokinase

Jamieson, S. A.·Pudjihartono, M.·Horne, C.·Day, R. C.·Murphy, J. M.·Mace, P. D.
View original source ↗Export metadata ↓

Abstract

Tribbles proteins (TRIB1-3) are a pseudokinase-only branch of the human kinome, which recruit substrates to the COP1 ubiquitin-ligase for ubiquitination. TRIB2 was the first Tribbles ortholog to be implicated as a myeloid leukaemia oncogene, by way of recruiting the C/EBPa transcription factor for degradation by COP1. Here we report selection and characterisation of nanobodies against the TRIB2 pseudokinase domain from a synthetic yeast surface-display library. We identified nanobodies that bind the TRIB2 pseudokinase domain with low nanomolar affinity. A crystal structure of Nb4.103 in complex with TRIB2 identified a mode of binding to the N-terminal lobe of the pseudokinase, in a manner that enables specific recognition of TRIB2 over TRIB1 and TRIB3. In the nanobody-stabilised state, TRIB2 adopts an activated conformation that is remarkably similar to the C/EBPa-bound state of TRIB1. Characterization in solution revealed that Nb4.103 can stabilise a TRIB2 pseudokinase domain dimer in a face-to-face manner. Conversely, a distinct nanobody (Nb4.101) binds through a similar epitope but does not readily promote dimerization. In combination, this study identifies features of TRIB2 that could be exploited for the development of inhibitors, and nanobody tools for future investigation of TRIB2 function.

Source connections

Explore related subjects

biochemistryPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Jamieson, S. A., Pudjihartono, M., Horne, C., Day, R. C., Murphy, J. M., Mace, P. D.. 2022-04-30. Nanobodies identify an activated state of the TRIB2 pseudokinase. https://doi.org/10.1101/2022.04.29.489987

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

EngA adopts multiple distinct conformational states during ribosome assembly

Ribosome assembly, a highly coordinated and crucial cellular process, is assisted by various assembly factors, including GTPases. EngA, an essential P-loop GTPase, is involved in late-stage assembly of the 50S ribosomal subunit. The structures of 50S ribosome in complex with EngA-bound GMPPNP, and EngA-bound GDP alone, without 50S subunit, have been reported previously. However, the molecular mechanism of EngA GTP hydrolysis-assisted 50S maturation remains poorly understood, and structures of the 50S ribosome in complex with EngA-bound GDP have yet to be deciphered. We have reported cryo- EM structures of the Mycobacterium smegmatis 50S ribosome in complex with EngA-bound GTP{gamma}S or GDP at 2.8 - 3.5 [A] resolution. Structural analysis revealed that EngA and 50S subunit undergo a coordinated structural rearrangement, and an assembly intermediate is formed in which the stem-loop of H80 makes base-pair interactions with the junction of H89 and H90, forming a unique stem-loop-junction (SLJ) motif. EngA-bound GDP adopts distinctly different conformations in its ribosome-bound and unbound states. In summary, this study proposed a multi-state conformational model for EngA-assisted ribosome assembly.

biochemistry↗
bioRxiv2026

Modular assembly of mitochondrial complex III from a dynamic matrix domain pool

Mitochondrial complex III is a central component of the cellular energy metabolism. It is an obligate dimer of catalytic and accessory subunits that are encoded by two genomes. How its large matrix domain, formed by the core proteins Qcr1 and Qcr2, is built and joined to the membrane part and during assembly is not known. Here we show that Qcr1 and Qcr2 preassemble independently of complex III into matrix domain modules. Cryo-EM structures from a cardiolipin-deficient yeast strain and of recombinant protein resolved single, double and triple matrix domains, which are linked by the C-terminal tail of Qcr1. In the mature complex III, the same tail binds cytochrome b and cardiolipin. The modules form a dynamic pool, in which assembly species interconvert and exchange subunits. Mutations at the module interfaces, including mimics of human disease variants, reshape this pool and deletion of the Qcr1 tail impairs respiratory growth. Substitution of a tyrosine residue linked to parkinsonism exposes a conserved cysteine residue to oxidation. A cryo-EM structure of an assembly intermediate shows a cap of two matrix domains bound to a monomeric membrane module of cytochrome b, Qcr7, Qcr8 and cytochrome c1. We propose that complex III receives its matrix domain from a dynamic pool of prebuilt modules, which organizes the dimerization of the complex.

biochemistry↗
bioRxiv2026

Vasopressin V2 receptor phosphopeptide reshapes the conformational landscape of arrestin-2 beyond C-tail detachment

Binding of phosphorylated GPCR tails influences arrestin conformation, but the contribution of this interaction to the interdomain rotation associated with activation remains incompletely characterised. In particular, it remains unclear whether displacement of the arrestin C-tail is sufficient to favor larger interdomain rotations or whether the bound phosphotail exerts an additional effect on the conformational landscape. Here, we used enhanced-sampling simulations to characterise the conformational free-energy landscapes of basal (unbound) and V2Rpp-bound arrestin-2. We find that V2Rpp binding broadened the range of energetically accessible interdomain rotation angles relative to basal arrestin-2. However, the pronounced rotation observed in the experimental structures, while accessible, was not strongly favored. Strikingly, C-tail displacement alone does not reproduce this effect, as arrestin-2 retains a strong preference for small interdomain rotation angles in the absence of V2Rpp. Moreover, the C-tail-detached state is energetically unfavorable in the absence of V2Rpp. Together, these findings quantify the effects of V2Rpp binding on the interdomain rotation of arrestin-2 and disentangle the effects of phosphopeptide binding from those of C-tail detachment.

biochemistry↗