---
OA_place: publisher
OA_type: hybrid
_id: '22148'
abstract:
- lang: eng
  text: 'How the twin-arginine translocase (Tat) system transports fully folded substrate
    proteins across cellular membranes without disrupting membrane integrity has been
    a fundamental question in cell biology for decades. The Tat system, found in prokaryotes
    and plant organelles, recognizes a cargo signal peptide via a conserved twin-arginine
    motif. The multi-subunit Tat complex facilitates the proton-motive-force-dependent
    translocation process, yet its overall architecture has remained unknown. Here,
    we present the cryo-electron microscopy (cryo-EM) structure of the Escherichia
    coli (E. coli) trimeric TatB₃C₃ complex with bound substrate SufI, assembled in
    vivo. The complex adopts an unusual, wide-open, bowl-shaped architecture with
    a polar inner cavity. Unexpectedly, the cargo is engaged in a dual-contact mode:
    while the signal peptide binds inside one TatBC unit, the folded domain docks
    tightly onto an adjacent unit, possibly performing a proofreading function. This
    structure provides a mechanistic framework for substrate engagement and suggests
    the direct involvement of the entire Tat complex in substrate translocation.'
acknowledged_ssus:
- _id: EM-Fac
- _id: ScienComp
acknowledgement: We thank IST Austria for providing the funding. We thank IST Austria
  EM facility for the use of Titan Krios TEM. Data processing was performed using
  IST high-performance computer cluster. We thank Dr. R. Roemhild and Professor C.
  Guet (ISTA) for help in constructing Tat deletion strains and Dr. A. Charnagalov
  (ISTA) for technical help.
article_processing_charge: Yes (via OA deal)
article_type: original
author:
- first_name: Ziyu
  full_name: Zhao, Ziyu
  id: a63fe682-9f3a-11ee-bf8c-cfdf919b9850
  last_name: Zhao
- first_name: Leonid A
  full_name: Sazanov, Leonid A
  id: 338D39FE-F248-11E8-B48F-1D18A9856A87
  last_name: Sazanov
  orcid: 0000-0002-0977-7989
biorxivid: 1
citation:
  ama: Zhao Z, Sazanov LA. Structure of E. Coli twin-arginine translocase (Tat) complex
    with bound cargo. <i>Molecular Cell</i>. doi:<a href="https://doi.org/10.1016/j.molcel.2026.05.026">10.1016/j.molcel.2026.05.026</a>
  apa: Zhao, Z., &#38; Sazanov, L. A. (n.d.). Structure of E. Coli twin-arginine translocase
    (Tat) complex with bound cargo. <i>Molecular Cell</i>. Elsevier. <a href="https://doi.org/10.1016/j.molcel.2026.05.026">https://doi.org/10.1016/j.molcel.2026.05.026</a>
  chicago: Zhao, Ziyu, and Leonid A Sazanov. “Structure of E. Coli Twin-Arginine Translocase
    (Tat) Complex with Bound Cargo.” <i>Molecular Cell</i>. Elsevier, n.d. <a href="https://doi.org/10.1016/j.molcel.2026.05.026">https://doi.org/10.1016/j.molcel.2026.05.026</a>.
  ieee: Z. Zhao and L. A. Sazanov, “Structure of E. Coli twin-arginine translocase
    (Tat) complex with bound cargo,” <i>Molecular Cell</i>. Elsevier.
  ista: Zhao Z, Sazanov LA. Structure of E. Coli twin-arginine translocase (Tat) complex
    with bound cargo. Molecular Cell.
  mla: Zhao, Ziyu, and Leonid A. Sazanov. “Structure of E. Coli Twin-Arginine Translocase
    (Tat) Complex with Bound Cargo.” <i>Molecular Cell</i>, Elsevier, doi:<a href="https://doi.org/10.1016/j.molcel.2026.05.026">10.1016/j.molcel.2026.05.026</a>.
  short: Z. Zhao, L.A. Sazanov, Molecular Cell (n.d.).
corr_author: '1'
das_tickbox: '1'
dataavailabilitystatement: "This study did not generate new unique reagents. Strains
  and plasmids generated in this study are available from the lead contact without
  restrictions.\r\n• Source data are provided within this paper. The cryo-EM map is
  deposited in the Electron Microscopy Data Bank under accession number EMD-53848.
  The model is deposited in the Protein Data Bank under accession number 9R91. The
  structural data are publicly available as of the date of publication. Raw images
  of spot assays, SDS-PAGE and BN-PAGE gels with Coomassie staining and immunoblot
  images are available at Mendeley Data (https://doi.org/10.17632/v2g3p9n985.1).\r\n•
  This paper does not report original code.\r\n• Any additional information required
  to reanalyze the data reported in this paper is available from the lead contact
  upon request."
date_created: 2026-06-28T22:01:35Z
date_published: 2026-06-22T00:00:00Z
date_updated: 2026-08-12T12:08:44Z
day: '22'
ddc:
- '570'
department:
- _id: LeSa
doi: 10.1016/j.molcel.2026.05.026
external_id:
  biorxivid:
  - 10.1101/2025.09.16.676506
fulldoi: https://doi.org/10.1016/j.molcel.2026.05.026
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc/4.0/
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1016/j.molcel.2026.05.026
month: '06'
oa: 1
oa_version: Published Version
publication: Molecular Cell
publication_identifier:
  eissn:
  - 1097-4164
  issn:
  - 1097-2765
publication_status: inpress
publisher: Elsevier
quality_controlled: '1'
related_material:
  link:
  - description: News on ISTA website
    relation: press_release
    url: https://ista.ac.at/en/news/the-gate-for-bulky-cargo/
  record:
  - id: '22189'
    relation: research_data
    status: public
researchdata_availability: yes
scopus_import: '1'
status: public
supplementarymaterial: yes
title: Structure of E. Coli twin-arginine translocase (Tat) complex with bound cargo
tmp:
  image: /images/cc_by_nc.png
  legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
  short: CC BY-NC (4.0)
type: journal_article
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2026'
...
---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '22750'
abstract:
- lang: eng
  text: 'Robust oxygenic photosynthesis requires the efficient assembly and repair
    of the multi-subunit oxygen-evolving photosystem II (PSII) complex. Previous cryogenic
    electron microscopy (cryo-EM) structures of PSII assembly/disassembly intermediates
    have relied on the analysis of deletion mutants or removal of PSII subunits in
    vitro. Here we report the cryo-EM structures of naturally occurring dimeric PSII
    intermediates from the cyanobacterium Thermosynechococcus vestitus at a resolution
    of about 2.2 Å. These intermediates contain inactive dimers lacking the oxygen-evolving
    complex (OEC) and semi-active dimers with the OEC present in one of the two monomers.
    Our structural data provide a mechanism for how assembly and disassembly of the
    Mn4CaO5 cluster is coordinated with the binding and release of the extrinsic proteins:
    restructuring of the C-terminal tail of D1 subunit during assembly or disassembly
    of the Mn cluster triggers conformational changes in D2, CP47 and CP43 to drive
    the binding/release of the extrinsic proteins. A combination of structural and
    mass spectrometry data also suggests that the inactive PSII complexes may include
    damaged complexes containing oxidized D1-His332, a monodentate ligand to one of
    the Mn ions of the OEC.'
acknowledged_ssus:
- _id: EM-Fac
- _id: LifeSc
- _id: ScienComp
acknowledgement: 'P.J.N. is grateful for the support from the Imperial College Electron
  Microscopy Center. L.A.S. acknowledges the support from the Scientific Service Units
  (SSU) of IST Austria: the Electron Microscopy Facility (EMF), the Life Science Facility
  (LSF) and the IST high-performance computing cluster. P.J.N. is grateful for the
  support of the Biotechnology & Biological Sciences Research Council (awards BB/I00937X/1,
  BB/L003260/1 and BB/P00931X/1). L.A.S. is grateful to IST Austria for providing
  the funding.'
article_number: '8433'
article_processing_charge: Yes
article_type: original
author:
- first_name: Ziyu
  full_name: Zhao, Ziyu
  id: a63fe682-9f3a-11ee-bf8c-cfdf919b9850
  last_name: Zhao
- first_name: Irene
  full_name: Vercellino, Irene
  id: 3ED6AF16-F248-11E8-B48F-1D18A9856A87
  last_name: Vercellino
  orcid: 0000-0001-5618-3449
- first_name: Julian P.
  full_name: Whitelegge, Julian P.
  last_name: Whitelegge
- first_name: Karim
  full_name: Maghlaoui, Karim
  last_name: Maghlaoui
- first_name: Wojciech
  full_name: Białek, Wojciech
  last_name: Białek
- first_name: Peter J.
  full_name: Nixon, Peter J.
  last_name: Nixon
- first_name: Leonid A
  full_name: Sazanov, Leonid A
  id: 338D39FE-F248-11E8-B48F-1D18A9856A87
  last_name: Sazanov
  orcid: 0000-0002-0977-7989
citation:
  ama: Zhao Z, Vercellino I, Whitelegge JP, et al. Cryo-EM structures of naturally
    occurring dimeric photosystem II complexes lacking the Mn4CaO5 cluster. <i>Nature
    Communications</i>. 2026;17. doi:<a href="https://doi.org/10.1038/s41467-026-75324-x">10.1038/s41467-026-75324-x</a>
  apa: Zhao, Z., Vercellino, I., Whitelegge, J. P., Maghlaoui, K., Białek, W., Nixon,
    P. J., &#38; Sazanov, L. A. (2026). Cryo-EM structures of naturally occurring
    dimeric photosystem II complexes lacking the Mn4CaO5 cluster. <i>Nature Communications</i>.
    Springer Nature. <a href="https://doi.org/10.1038/s41467-026-75324-x">https://doi.org/10.1038/s41467-026-75324-x</a>
  chicago: Zhao, Ziyu, Irene Vercellino, Julian P. Whitelegge, Karim Maghlaoui, Wojciech
    Białek, Peter J. Nixon, and Leonid A Sazanov. “Cryo-EM Structures of Naturally
    Occurring Dimeric Photosystem II Complexes Lacking the Mn4CaO5 Cluster.” <i>Nature
    Communications</i>. Springer Nature, 2026. <a href="https://doi.org/10.1038/s41467-026-75324-x">https://doi.org/10.1038/s41467-026-75324-x</a>.
  ieee: Z. Zhao <i>et al.</i>, “Cryo-EM structures of naturally occurring dimeric
    photosystem II complexes lacking the Mn4CaO5 cluster,” <i>Nature Communications</i>,
    vol. 17. Springer Nature, 2026.
  ista: Zhao Z, Vercellino I, Whitelegge JP, Maghlaoui K, Białek W, Nixon PJ, Sazanov
    LA. 2026. Cryo-EM structures of naturally occurring dimeric photosystem II complexes
    lacking the Mn4CaO5 cluster. Nature Communications. 17, 8433.
  mla: Zhao, Ziyu, et al. “Cryo-EM Structures of Naturally Occurring Dimeric Photosystem
    II Complexes Lacking the Mn4CaO5 Cluster.” <i>Nature Communications</i>, vol.
    17, 8433, Springer Nature, 2026, doi:<a href="https://doi.org/10.1038/s41467-026-75324-x">10.1038/s41467-026-75324-x</a>.
  short: Z. Zhao, I. Vercellino, J.P. Whitelegge, K. Maghlaoui, W. Białek, P.J. Nixon,
    L.A. Sazanov, Nature Communications 17 (2026).
corr_author: '1'
das_tickbox: '1'
dataavailabilitystatement: The cryo-EM maps are deposited in the Electron Microscopy
  Data Bank under accession number EMD- 51100 (inactive dimer), EMD- 51102 (active
  dimer) and EMD-51101 (semi-active dimer). The models are deposited in the Protein
  Data Bank under accession numbers 9G6F (inactive dimer), 9G6H (active dimer) and
  9G6G (semi-active dimer). Mass spectrometry data was uploaded to MassIVE with accession
  code MSV000101057. Source data are provided with this paper.
date_created: 2026-08-23T22:01:46Z
date_published: 2026-08-17T00:00:00Z
date_updated: 2026-09-07T13:17:53Z
day: '17'
ddc:
- '570'
department:
- _id: LeSa
doi: 10.1038/s41467-026-75324-x
external_id:
  pmid:
  - '42420307'
file:
- access_level: open_access
  checksum: a820b736585de22bcfa30ebdd25a6dd2
  content_type: application/pdf
  creator: dernst
  date_created: 2026-09-07T13:13:03Z
  date_updated: 2026-09-07T13:13:03Z
  file_id: '22843'
  file_name: 2026_NatureComm_Zhao.pdf
  file_size: 3370665
  relation: main_file
  success: 1
file_date_updated: 2026-09-07T13:13:03Z
fulldoi: https://doi.org/10.1038/s41467-026-75324-x
has_accepted_license: '1'
intvolume: '        17'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-nd/4.0/
month: '08'
oa: 1
oa_version: Published Version
pmid: 1
publication: Nature Communications
publication_identifier:
  eissn:
  - 2041-1723
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
researchdata_availability: yes
scopus_import: '1'
status: public
supplementarymaterial: yes
title: Cryo-EM structures of naturally occurring dimeric photosystem II complexes
  lacking the Mn4CaO5 cluster
tmp:
  image: /images/cc_by_nc_nd.png
  legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
    (CC BY-NC-ND 4.0)
  short: CC BY-NC-ND (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 17
year: '2026'
...