A new family of bacterial ribosome hibernation factors

Nature, Год журнала: 2024, Номер 626(8001), С. 1125 - 1132

Опубликована: Фев. 14, 2024

Abstract To conserve energy during starvation and stress, many organisms use hibernation factor proteins to inhibit protein synthesis protect their ribosomes from damage 1,2 . In bacteria, two families of factors have been described, but the low conservation these huge diversity species, habitats environmental stressors confounded discovery 3–6 Here, by combining cryogenic electron microscopy, genetics biochemistry, we identify Balon, a new in cold-adapted bacterium Psychrobacter urativorans We show that Balon is distant homologue archaeo-eukaryotic translation aeRF1 found 20% representative bacteria. During cold shock or stationary phase, occupies ribosomal A site both vacant actively translating complex with EF-Tu, highlighting an unexpected role for EF-Tu cellular stress response. Unlike typical A-site substrates, binds mRNA-independent manner, initiating mode ribosome can commence while are still engaged synthesis. Our work suggests Balon–EF-Tu-regulated ubiquitous bacterial stress-response mechanism, demonstrate putative homologues Mycobacteria bind similar fashion. This finding calls revision current model inferred common holds numerous implications how understand study hibernation.

Язык: Английский

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Functional annotation of a divergent genome using sequence and structure-based similarity

BMC Genomics, Год журнала: 2024, Номер 25(1)

Опубликована: Янв. 2, 2024

Microsporidia are a large taxon of intracellular pathogens characterized by extraordinarily streamlined genomes with unusually high sequence divergence and many species-specific adaptations. These unique factors pose challenges for traditional genome annotation methods based on similarity. As result, the microsporidian sequenced to date contain numerous genes unknown function. Recent innovations in rapid accurate structure prediction comparison, together growing amount data structural databases, provide new opportunities assist functional newly genomes.

Язык: Английский

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Mechanisms and regulation of substrate degradation by the 26S proteasome

Nature Reviews Molecular Cell Biology, Год журнала: 2024, Номер unknown

Опубликована: Окт. 3, 2024

Язык: Английский

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Ultrastructural insights into the microsporidian infection apparatus reveal the kinetics and morphological transitions of polar tube and cargo during host cell invasion

PLoS Biology, Год журнала: 2024, Номер 22(2), С. e3002533 - e3002533

Опубликована: Фев. 29, 2024

During host cell invasion, microsporidian spores translocate their entire cytoplasmic content through a thin, hollow superstructure known as the polar tube. To achieve this, tube transitions from compact spring-like state inside environmental spore to long needle-like capable of long-range sporoplasm delivery. The unique mechanical properties building blocks allow for an explosive transition extended and support rapid cargo translocation process. molecular structural factors enabling this ultrafast process changes during delivery are unknown. Here, we employ light microscopy in situ cryo-electron tomography visualize multiple ultrastructural states Vairimorpha necatrix tube, allowing us evaluate kinetics its germination characterize underlying morphological transitions. We describe cargo-filled with ordered arrangement ribosomes, which cluster along thin wall, empty post-translocation reduced diameter but thicker wall. Together proteomic analysis endogenously affinity-purified tubes, our work provides comprehensive data on infection apparatus microsporidia uncovers new aspects ribosome regulation transport.

Язык: Английский

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Ηigh-resolution structure of mammalian PI31–20S proteasome complex reveals mechanism of proteasome inhibition

Journal of Biological Chemistry, Год журнала: 2023, Номер 299(7), С. 104862 - 104862

Опубликована: Май 25, 2023

Proteasome-catalyzed protein degradation mediates and regulates critical aspects of many cellular functions is an important element proteostasis in health disease. Proteasome function determined part by the types proteasome holoenzymes formed between 20S core particle that catalyzes peptide bond hydrolysis any multiple regulatory proteins to which it binds. One these regulators, PI31, was previously identified as vitro inhibitor, but neither molecular mechanism nor possible physiologic significance PI31-mediated inhibition has been clear. Here we report a high-resolution cryo-EM structure mammalian complex with PI31. The shows two copies intrinsically disordered carboxyl terminus PI31 are present central cavity closed-gate conformation interact catalytic sites manner blocks proteolysis substrates resists their own degradation. inhibitory polypeptide chains appear originate from monomers enter chamber opposite ends cylinder. We evidence can inhibit activity cells may serve for control proteostasis.

Язык: Английский

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Study of an FBXO7 patient mutation reveals Fbxo7 and PI31 co‐regulate proteasomes and mitochondria

FEBS Journal, Год журнала: 2024, Номер 291(12), С. 2565 - 2589

Опубликована: Март 11, 2024

Mutations in FBXO7 have been discovered to be associated with an atypical parkinsonism. We report here a new homozygous missense mutation paediatric patient that causes L250P substitution the dimerisation domain of Fbxo7. This alteration selectively ablates Fbxo7‐PI31 interaction and significant reduction Fbxo7 PI31 levels cells. Consistent their association proteasomes, fibroblasts reduced proteasome activity subunits. also show interacts MiD49/51 fission adaptor proteins, unexpectedly, acts facilitate SCF ‐mediated ubiquitination MiD49. The reduces ligase‐mediated subset its known substrates. Although expression was cells, there no effect on mitochondrial network. However, cells function mitophagy, higher ROS are less viable under stress. Our study demonstrates regulate proteasomes mitochondria reveals for enhancing E3 ubiquitin ligase activity.

Язык: Английский

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Rippling life on a dormant planet: hibernation of ribosomes, RNA polymerases, and other essential enzymes

Frontiers in Microbiology, Год журнала: 2024, Номер 15

Опубликована: Май 6, 2024

Throughout the tree of life, cells and organisms enter states dormancy or hibernation as a key feature their biology: from bacterium arresting its growth in response to starvation, plant seed anticipating placement fertile ground, human oocyte poised for fertilization create new life. Recent research shows that when hibernate, many essential enzymes hibernate too: they disengage substrates associate with specialized group proteins known factors. Here, we summarize how factors protect cellular undesired activity irreparable damage hibernating cells. We show molecular hibernation, once viewed rare exclusive certain molecules like ribosomes, is fact widespread property biological required sustained persistence life on Earth.

Язык: Английский

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PI31 is a positive regulator of 20S immunoproteasome assembly

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2025, Номер unknown

Опубликована: Янв. 15, 2025

PI31 ( P roteasome Inhibitor of 31 ,000 Da) is a 20S proteasome-binding protein originally identified as an inhibitor in vitro proteasome activity. Although recent studies have provided detailed structural basis for this activity, the physiologic significance PI31-mediated inhibition remains uncertain and alternative cellular roles been described. Here we report role positive regulator assembly immuno-proteasome (20Si), compositionally functionally distinct isoform that poorly inhibited by PI31. Genetic ablation mammalian cells had no effect on content or activity constitutively expressed proteasomes but reduced interferon-γ-induced immuno-proteasomes. This selective consequence defective 20Si assembly, indicated accumulation intermediates. Our results highlight distinction pathways constitutive immuno-proteasomes indicate plays chaperone-like immunoproteasomes.

Язык: Английский

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Rapaprotin is Activated by an Endopeptidase to Disassemble 26S Proteasome

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2025, Номер unknown

Опубликована: Фев. 27, 2025

The 19S regulatory particle (RP) associates with the 20S core (CP) to form 26S proteasome, an evolutionarily conserved holoenzyme that plays key roles in both physiological and pathological processes. Proteasome inhibitors target catalytic subunits within have proven be valuable research tools therapeutics for various cancers. Herein we report discovery of rapaprotin, a proteasome assembly inhibitor from our natural product-inspired hybrid macrocycle rapafucin library. Rapaprotin induces apoptosis myeloma leukemia cell lines. Genome-wide CRISPR-Cas9 screen identified cytosolic enzyme, prolyl endopeptidase (PREP) is required pro-apoptotic activity rapaprotin. Further mechanistic studies revealed rapaprotin acts as molecular transformer, changing inactive cyclic into active linear form, rapaprotin-L, upon PREP cleavage, block activity. Time-resolved cryogenic electron microscopy (cryo-EM) rapaprotin-L dissociation RP holoenzyme, which was verified cells. Furthermore, exhibits marked synergistic effect FDA-approved resensitizes drug-resistant multiple cells patients bortezomib. Taken together, these results suggest new chemical tool probe dynamics promising anticancer drug lead.

Язык: Английский

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Differential Interactions of the Proteasome Inhibitor PI31 with Constitutive and Immuno-20S Proteasomes

Biochemistry, Год журнала: 2024, Номер 63(8), С. 1000 - 1015

Опубликована: Апрель 5, 2024

PI31 (Proteasome Inhibitor of 31,000 Da) is a 20S proteasome binding protein originally identified as an in vitro inhibitor proteolytic activity. Recently reported cryo-electron microscopy structures 20S–PI31 complexes have revealed that the natively disordered proline-rich C-terminus enters central chamber interior and interacts directly with proteasome's multiple catalytic threonine residues manner predicted to inhibit their enzymatic function while evading its own proteolysis. Higher eukaryotes express alternative form (termed "immuno-proteasome") features genetically functionally distinct subunits. The effect on immuno-proteasome unknown. We examine relative inhibitory effects purified constitutive (20Sc) immuno-(20Si) proteasomes show inhibits 20Si hydrolytic activity significantly lesser degree than 20Sc. Unlike 20Sc, hydrolyzes carboxyl-terminus this contributes reduced toward 20Si. Conversely, loss 20Sc inhibition by point mutants leads degradation These results demonstrate unexpected differential interactions document functional consequences.

Язык: Английский

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