Structural analysis of the dynamic ribosome-translocon complex DOI Creative Commons
Aaron J. O. Lewis,

Frank Zhong,

Robert J. Keenan

et al.

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: Dec. 22, 2023

Abstract The protein translocon at the endoplasmic reticulum comprises Sec61 translocation channel and numerous accessory factors that collectively facilitate biogenesis of secretory membrane proteins. Here, we leveraged recent advances in cryo-EM structure prediction to derive insights into several novel configurations ribosome-translocon complex. We show how a transmembrane domain (TMD) looped configuration passes through lateral gate during insertion; nascent chain can bind constrain conformation ribosomal uL22; translocon-associated (TRAP) complex adjust its position different stages biogenesis. Most unexpectedly, find large proportion complexes contains RAMP4 intercalated Sec61’s gate, widening central pore contributing hydrophilic interior. These structures lead mechanistic hypotheses for function highlight remarkably plastic machinery whose conformations composition dynamically diverse range substrates.

Language: Английский

Cotranslational sorting and processing of newly synthesized proteins in eukaryotes DOI Creative Commons
Martin Gamerdinger, Elke Deuerling

Trends in Biochemical Sciences, Journal Year: 2023, Volume and Issue: 49(2), P. 105 - 118

Published: Nov. 1, 2023

Ribosomes interact with a variety of different protein biogenesis factors that guide newly synthesized proteins to their native 3D shapes and cellular localization. Depending on the type translated substrate, distinct set cotranslational must ribosome in timely coordinated manner ensure proper biogenesis. While cytonuclear require maturation folding factors, secretory be maintained an unfolded state processed cotranslationally by transport membrane translocation factors. Here we explore specific processing steps for cytonuclear, secretory, eukaryotes then discuss how nascent polypeptide-associated complex (NAC) sorts these into correct pathway.

Language: Английский

Citations

26
ER Stress as a Sentinel Mechanism for ER Ca2+ Homeostasis DOI Creative Commons

Tadashi Makio,

Junsheng Chen, Thomas Simmen

et al.

Cell Calcium, Journal Year: 2024, Volume and Issue: 124, P. 102961 - 102961

Published: Oct. 18, 2024

Language: Английский

Citations

7
Structural insights into TRAP association with ribosome-Sec61 complex and translocon inhibition by a CADA derivative DOI Creative Commons
Eva Pauwels, Neesha R. Shewakramani, Brent De Wijngaert

et al.

Science Advances, Journal Year: 2023, Volume and Issue: 9(9)

Published: March 3, 2023

During cotranslational translocation, the signal peptide of a nascent chain binds Sec61 translocon to initiate protein transport through endoplasmic reticulum (ER) membrane. Our cryo-electron microscopy structure ribosome-Sec61 shows binding an ordered heterotetrameric translocon-associated (TRAP) complex, in which TRAP-γ is anchored at two adjacent positions 28

Language: Английский

Citations

16
The dynamic architecture of Map1- and NatB-ribosome complexes coordinates the sequential modifications of nascent polypeptide chains DOI Creative Commons
Alexandra Knorr, Timur Mackens‐Kiani,

Joanna Musial

et al.

PLoS Biology, Journal Year: 2023, Volume and Issue: 21(4), P. e3001995 - e3001995

Published: April 20, 2023

Cotranslational modification of the nascent polypeptide chain is one first events during birth a new protein. In eukaryotes, methionine aminopeptidases (MetAPs) cleave off starter methionine, whereas N-acetyl-transferases (NATs) catalyze N-terminal acetylation. MetAPs and NATs compete with other cotranslationally acting chaperones, such as ribosome-associated complex (RAC), protein targeting translocation factors (SRP Sec61) for binding sites at ribosomal tunnel exit. Yet, well-resolved structures ribosome-bound RAC, SRP Sec61, are available, structural information on mode ribosome interaction eukaryotic or five active only available NatA. Here, we present cryo-EM yeast Map1 NatB bound to ribosome-nascent complexes. mainly associated dynamic rRNA expansion segment ES27a, thereby kept an ideal position below exit act emerging substrate chain. For NatB, observe two copies complex. NatB-1 binds directly exit, again involving NatB-2 located second universal adapter site (eL31 uL22). The complexes differs but overlaps that NatA Map1, implying exclusively We further ES27a adopts distinct conformations when NatA, together suggesting contribution coordination sequential activity these tunnel.

Language: Английский

Citations

15
Cytoplasmic ribosomes on mitochondria alter the local membrane environment for protein import DOI
Ya‐Ting Chang, Benjamin A. Barad,

Juliette Hamid

et al.

The Journal of Cell Biology, Journal Year: 2025, Volume and Issue: 224(4)

Published: March 6, 2025

Most of the mitochondria proteome is nuclear-encoded, synthesized by cytoplasmic ribosomes, and targeted to posttranslationally. However, a subset mitochondrial-targeted proteins imported co-translationally, although molecular mechanisms governing this process remain unclear. We employ cellular cryo-electron tomography visualize interactions between ribosomes in Saccharomyces cerevisiae. use surface morphometrics tools identify optimally oriented on mitochondrial membranes for protein import. This allows us establish first subtomogram average structure ribosome at native context, which showed three distinct connections with outer membrane surrounding peptide exit tunnel. Further, analysis demonstrated that primed import cluster sites local constrictions inner membranes. Overall, our study reveals architecture spatial organization surface, providing context define mediate efficient co-translational

Language: Английский

Citations

0
Molecular view of ER membrane remodeling by the Sec61/TRAP translocon DOI Creative Commons
Sudeep Karki, Matti Javanainen, Shahid Rehan

et al.

EMBO Reports, Journal Year: 2023, Volume and Issue: 24(12)

Published: Nov. 20, 2023

Protein translocation across the endoplasmic reticulum (ER) membrane is an essential step during protein entry into secretory pathway. The conserved Sec61 protein-conducting channel facilitates polypeptide and coordinates cotranslational polypeptide-processing events. In cells, majority of stably associated with a heterotetrameric complex, translocon-associated complex (TRAP), yet mechanism by which TRAP assists in remains unknown. Here, we present structure core Sec61/TRAP bound to mammalian ribosome cryogenic electron microscopy (cryo-EM). Ribosome interactions anchor conformation that renders ER locally thinner significantly curving its lumenal leaflet. We propose stabilizes exit tunnel assist nascent insertion through provides ratcheting lumen mediated direct interactions.

Language: Английский

Citations

9
Exploring the molecular composition of the multipass translocon in its native membrane environment DOI Creative Commons
Max Gemmer, Marten L. Chaillet, Friedrich Förster

et al.

Life Science Alliance, Journal Year: 2024, Volume and Issue: 7(8), P. e202302496 - e202302496

Published: June 12, 2024

Multispanning membrane proteins are inserted into the endoplasmic reticulum by ribosome-bound multipass translocon (MPT) machinery. Based on cryo-electron tomography and extensive subtomogram analysis, we reveal composition arrangement of MPT components in their native environment. The intramembrane chaperone complex PAT translocon-associated protein (TRAP) associate substoichiometrically with a translation-dependent manner. Although is preferentially part MPTs bound to translating ribosomes, abundance TRAP highest associated non-translating ribosomes. average TRAP-containing reveals intermolecular contacts between luminal domains an unknown subunit back-of-Sec61 complex. AlphaFold modeling suggests this nodal modulator, bridging nicalin TRAPα. Collectively, our results visualize variability factors environment dependent translational activity ribosome.

Language: Английский

Citations

3
Role of a holo-insertase complex in the biogenesis of biophysically diverse ER membrane proteins DOI
Katharine R. Page, Vy N. Nguyen, Tino Pleiner

et al.

Molecular Cell, Journal Year: 2024, Volume and Issue: 84(17), P. 3302 - 3319.e11

Published: Aug. 23, 2024

Language: Английский

Citations

2
Structural analysis of the dynamic ribosome-translocon complex DOI Creative Commons
Aaron J. O. Lewis,

Frank Zhong,

Robert J. Keenan

et al.

eLife, Journal Year: 2024, Volume and Issue: 13

Published: April 16, 2024

The protein translocon at the endoplasmic reticulum comprises Sec61 translocation channel and numerous accessory factors that collectively facilitate biogenesis of secretory membrane proteins. Here, we leveraged recent advances in cryo-electron microscopy (cryo-EM) structure prediction to derive insights into several novel configurations ribosome-translocon complex. We show how a transmembrane domain (TMD) looped configuration passes through lateral gate during insertion; nascent chain can bind constrain conformation ribosomal uL22; translocon-associated (TRAP) complex adjust its position different stages biogenesis. Most unexpectedly, find large proportion complexes contains RAMP4 intercalated Sec61’s gate, widening central pore contributing hydrophilic interior. These structures lead mechanistic hypotheses for function highlight remarkably plastic machinery whose conformations composition dynamically diverse range substrates.

Language: Английский

Citations

2
Structural analysis of the dynamic ribosome-translocon complex DOI Open Access
Aaron J. O. Lewis,

Frank Zhong,

Robert J. Keenan

et al.

Published: May 24, 2024

The protein translocon at the endoplasmic reticulum comprises Sec61 translocation channel and numerous accessory factors that collectively facilitate biogenesis of secretory membrane proteins. Here, we leveraged recent advances in cryo-EM structure prediction to derive insights into several novel configurations ribosome-translocon complex. We show how a transmembrane domain (TMD) looped configuration passes through lateral gate during insertion; nascent chain can bind constrain conformation ribosomal uL22; translocon-associated (TRAP) complex adjust its position different stages biogenesis. Most unexpectedly, find large proportion complexes contains RAMP4 intercalated Sec61’s gate, widening central pore contributing hydrophilic interior. These structures lead mechanistic hypotheses for function highlight remarkably plastic machinery whose conformations composition dynamically diverse range substrates.

Language: Английский

Citations

1