Biology subjects

Karpauskaite, L.

Publications and source records attributed to Karpauskaite, L..

3 recordsLinked to original sources

bioRxiv2026

Molecular determinants of cotranslational chaperone recruitment to nascent p53

Protein folding is fast relative to mRNA translation and nascent polypeptides begin to fold during their synthesis on the ribosome. The resulting cotranslational folding intermediates are accessible to diverse molecular chaperones that recognise incompletely folded client proteins. Here, we sought to understand how specific chaperone:client complexes are established during protein synthesis, using the chaperone-dependent tumor suppressor protein p53 as a model. By capturing interactomes at different points during p53 synthesis, we show that Hsp70, Hsp90 and TRiC bind competitively to nascent p53. While Hsp70 and Hsp90 bind promiscuously, TRiC discriminates between subtly different partially-folded states. TRiC recruitment is dictated by local cotranslational folding and exposure of specific sequence motifs, and this is tuned by cancer-associated mutations in the p53 DNA-binding domain. Nascent chain interactions with the ribosome surface disfavor TRiC binding, demonstrating that the ribosome imposes unique constraints on chaperone recruitment during protein synthesis. Our results establish molecular principles underlying chaperone prioritization during protein biogenesis.

biochemistry↗

bioRxiv2024

The human ribosome modulates multidomain protein biogenesis by delaying cotranslational domain docking

Proteins with multiple domains are intrinsically prone to misfold, yet fold efficiently during their synthesis on the ribosome. This is especially important in eukaryotes, where multidomain proteins predominate. Here, we sought to understand how multidomain protein folding is modulated by the eukaryotic ribosome. We used cryo-electron microscopy and hydrogen/deuterium exchange-mass spectrometry to characterise the structure and dynamics of partially-synthesised intermediates of a model multidomain protein. We find that nascent subdomains fold progressively during synthesis on the human ribosome, templated by interactions across domain interfaces. The conformational ensemble of the nascent chain is tuned by its unstructured C-terminal segments, which keep interfaces between folded domains in dynamic equilibrium until translation termination. This contrasts with the bacterial ribosome, on which domain interfaces form early and remain stable during synthesis. Delayed domain docking may avoid interdomain misfolding to promote the maturation of multidomain proteins in eukaryotes.

biochemistry↗

bioRxiv2020

Protein mimetic amyloid inhibitor potently abrogates cancer-associated mutant p53 aggregation and restores tumor suppressor function

Missense mutations in p53 are severely deleterious and occur in over 50% of all human cancers. The vast majority of these mutations are located in the inherently unstable DNA-binding domain (DBD), many of which destabilize the domain further and expose its aggregation-prone hydrophobic core, prompting self-assembly of mutant p53 into inactive cytosolic amyloid-like aggregates. Screening an oligopyridylamide library, previously shown to inhibit amyloid formation associated with Alzheimers disease and type II diabetes, identified a tripyridylamide, ADH-6, that potently abrogates self-assembly of the aggregation-nucleating subdomain of mutant p53 DBD. Moreover, ADH-6 effectively targets and dissociates mutant p53 aggregates in human cancer cells, which restores p53s transcriptional activity, leading to cell cycle arrest and apoptosis. Notably, ADH-6 treatment substantially shrinks xenografts harboring mutant p53 and prolongs survival, while exhibiting no toxicity to healthy tissue. This study demonstrates the first successful application of a bona fide small-molecule amyloid inhibitor as an anticancer agent.

cancer biology↗