Visualization of translation and protein biogenesis at the ER membrane

Nature, Год журнала: 2023, Номер 614(7946), С. 160 - 167

Опубликована: Янв. 25, 2023

The dynamic ribosome-translocon complex, which resides at the endoplasmic reticulum (ER) membrane, produces a major fraction of human proteome1,2. It governs synthesis, translocation, membrane insertion, N-glycosylation, folding and disulfide-bond formation nascent proteins. Although individual components this machinery have been studied high resolution in isolation3-7, insights into their interplay native remain limited. Here we use cryo-electron tomography, extensive classification molecular modelling to capture snapshots mRNA translation protein maturation ER resolution. We identify highly abundant classical pre-translocation intermediate with eukaryotic elongation factor 1a (eEF1a) an extended conformation, suggesting that eEF1a may associated ribosome after GTP hydrolysis during proofreading. At distinct polysomes bind different translocons specialized synthesis proteins signal peptides or multipass transmembrane translocon-associated complex (TRAP) present both. near-complete atomic model most translocon variant comprising protein-conducting channel SEC61, TRAP oligosaccharyltransferase A (OSTA) reveals specific interactions other components. observe stoichiometric sub-stoichiometric cofactors OSTA, are likely include isomerases. In sum, visualize ER-bound coordinated downstream machinery.

Язык: Английский

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Mechanism of an intramembrane chaperone for multipass membrane proteins

Nature, Год журнала: 2022, Номер 611(7934), С. 161 - 166

Опубликована: Окт. 19, 2022

Язык: Английский

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Identification of TMEM126A as OXA1L-interacting protein reveals cotranslational quality control in mitochondria

Molecular Cell, Год журнала: 2024, Номер 84(2), С. 345 - 358.e5

Опубликована: Янв. 1, 2024

Cellular proteostasis requires transport of polypeptides across membranes. Although defective processes trigger cytosolic rescue and quality control mechanisms that clear translocases membranes from unproductive cargo, proteins are synthesized within mitochondria not accessible to these mechanisms. Mitochondrial-encoded inserted cotranslationally into the inner membrane by conserved insertase OXA1L. Here, we identify TMEM126A as a OXA1L-interacting protein. associates with mitochondrial ribosomes translation products. Loss leads destabilization products, triggering an process, in which newly degraded iAAA protease. Our data reveal cooperates OXA1L protein insertion membrane. Upon loss TMEM126A, cargo-blocked complexes undergo proteolytic clearance protease machinery together its cargo.

Язык: Английский

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Cotranslational Mechanisms of Protein Biogenesis and Complex Assembly in Eukaryotes

Annual Review of Biomedical Data Science, Год журнала: 2022, Номер 5(1), С. 67 - 94

Опубликована: Апрель 26, 2022

The formation of protein complexes is crucial to most biological functions. cellular mechanisms governing complex biogenesis are not yet well understood, but some principles cotranslational and posttranslational assembly beginning emerge. In bacteria, this process favored by operons encoding subunits complexes. Eukaryotic cells do have polycistronic mRNAs, raising the question how they orchestrate encounter unassembled subunits. Here we review constraints eukaryotic co- folding assembly, including influence elongation rate on nascent chain targeting, folding, chaperone interactions. Recent evidence shows that mRNAs oligomeric assemblies can undergo localized translation form cytoplasmic condensates might facilitate Understanding interplay between mRNA proteostasis will be critical defining in vivo.

Язык: Английский

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Membrane homeostasis beyond fluidity: control of membrane compressibility

Trends in Biochemical Sciences, Год журнала: 2023, Номер 48(11), С. 963 - 977

Опубликована: Авг. 29, 2023

Biomembranes are complex materials composed of lipids and proteins that compartmentalize biochemistry. They actively remodeled in response to physical metabolic cues, as well during cell differentiation stress. The concept homeoviscous adaptation has become a textbook example membrane responsiveness. Here, we discuss limitations common misconceptions revolving around it. By highlighting key moments the life cycle transmembrane protein, illustrate thickness finely regulated compressibility crucial facilitate proper protein insertion, function, sorting, inheritance. We propose unfolded (UPR) provides mechanism for endoplasmic reticulum (ER) homeostasis by sensing aberrant transverse stiffening triggering adaptive responses re-establish compressibility.

Язык: Английский

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EMC rectifies the topology of multipass membrane proteins

Nature Structural & Molecular Biology, Год журнала: 2023, Номер 31(1), С. 32 - 41

Опубликована: Ноя. 13, 2023

Most eukaryotic multipass membrane proteins are inserted into the of endoplasmic reticulum. Their transmembrane domains (TMDs) thought to be co-translationally as they emerge from a membrane-bound ribosome. Here we find that TMDs near carboxyl terminus mammalian post-translationally by reticulum protein complex (EMC). Site-specific crosslinking shows EMC's cytosol-facing hydrophilic vestibule is adjacent pre-translocated C-terminal tail. EMC-mediated insertion mostly agnostic TMD hydrophobicity, favored for short uncharged C-tails and stimulated preceding unassembled bundle. Thus, can released ribosome-translocon in an incompletely state, requiring separate post-translational step rectify their topology, complete biogenesis evade quality control. This sequential co-translational mechanism may apply ~250 diverse proteins, including subunits pentameric ion channel family crucial neurotransmission.

Язык: Английский

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Mechanism of signal-anchor triage during early steps of membrane protein insertion

Molecular Cell, Год журнала: 2023, Номер 83(6), С. 961 - 973.e7

Опубликована: Фев. 9, 2023

Most membrane proteins use their first transmembrane domain, known as a signal anchor (SA), for co-translational targeting to the endoplasmic reticulum (ER) via recognition particle (SRP). The SA then inserts into using either Sec61 translocation channel or ER protein complex (EMC) insertase. How EMC and collaborate ensure insertion in correct topology is not understood. Using site-specific crosslinking, we detect pre-insertion intermediate adjacent EMC. This forms after release from SRP but before ribosome transfer Sec61. polypeptide's N-terminal tail samples cytosolic vestibule bordered by EMC3, where it can translocate across concomitant with insertion. docks on Sec61, which has an opportunity insert those SAs skipped These results suggest that acts between triage during biogenesis.

Язык: Английский

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Molecular basis of the TRAP complex function in ER protein biogenesis

Nature Structural & Molecular Biology, Год журнала: 2023, Номер 30(6), С. 770 - 777

Опубликована: Май 11, 2023

Abstract The translocon-associated protein (TRAP) complex resides in the endoplasmic reticulum (ER) membrane and interacts with Sec translocon ribosome to facilitate biogenesis of secretory proteins. TRAP plays a key role secretion many hormones, including insulin. Here we reveal molecular architecture mammalian how it engages translating associated Sec61 on ER membrane. is anchored via long tether its position further stabilized by finger-like loop. This positions cradle-like lumenal domain below for interactions translocated nascent chains. Our structure-guided mutations Caenorhabditis elegans lead growth deficits increased stress defects hormone secretion. These findings elucidate basis translocation proteins at ER.

Язык: Английский

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Molecular insights of exercise therapy in disease prevention and treatment

Signal Transduction and Targeted Therapy, Год журнала: 2024, Номер 9(1)

Опубликована: Май 29, 2024

Despite substantial evidence emphasizing the pleiotropic benefits of exercise for prevention and treatment various diseases, underlying biological mechanisms have not been fully elucidated. Several attributed to signaling molecules that are released in response by different tissues such as skeletal muscle, cardiac adipose, liver tissue. These molecules, which collectively termed exerkines, form a heterogenous group bioactive substances, mediating inter-organ crosstalk well structural functional tissue adaption. Numerous scientific endeavors focused on identifying characterizing new mediators with properties. Additionally, some investigations molecular targets exerkines cellular cascades trigger adaption processes. A detailed understanding tissue-specific downstream effects is crucial harness health-related mediated improve targeted programs health disease. Herein, we review current vivo exerkine-induced signal transduction across multiple target highlight preventive therapeutic value exerkine diseases. By aspects research, provide comprehensive overview (i) underpinnings secretion, (ii) receptor-dependent receptor-independent adaption, (iii) clinical implications these disease treatment.

Язык: Английский

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Perilipin membrane integration determines lipid droplet heterogeneity in differentiating adipocytes

Cell Reports, Год журнала: 2024, Номер 43(4), С. 114093 - 114093

Опубликована: Апрель 1, 2024

The storage of fat within lipid droplets (LDs) adipocytes is critical for whole-body health. Acute fatty acid (FA) uptake by differentiating leads to the formation at least two LD classes marked distinct perilipins (PLINs). How this heterogeneity arises an important yet unresolved cell biological problem. Here, we show that unconventional integral membrane segment (iMS) targets adipocyte specific surface factor PLIN1 endoplasmic reticulum (ER) and facilitates high-affinity binding first class. other PLINs remain largely excluded from these LDs until FA influx recruits them a second population. Preventing ER targeting turns into soluble, cytoplasmic protein, reduces its affinity, switches class specificity. Conversely, moving iMS PLIN2 insertion separate Our results shed light on how differences in organelle disparities affinity factors contribute heterogeneity.

Язык: Английский

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