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Structural insights into the mechanism of protein transport by the Type 9 Secretion System translocon

Abstract:
Secretion systems are protein export machines that enable bacteria to exploit their environment through the release of protein effectors. The Type 9 Secretion System (T9SS) is responsible for protein export across the outer membrane (OM) of bacteria of the phylum Bacteroidota. Here we trap the T9SS of Flavobacterium johnsoniae in the process of substrate transport by disrupting the T9SS motor complex. Cryo-EM analysis of purified substrate-bound T9SS translocons reveals an extended translocon structure in which the previously described translocon core is augmented by a periplasmic structure incorporating the proteins SprE, PorD and a homologue of the canonical periplasmic chaperone Skp. Substrate proteins bind to the extracellular loops of a carrier protein within the translocon pore. As transport intermediates accumulate on the translocon when energetic input is removed, we deduce that release of the substrate–carrier protein complex from the translocon is the energy-requiring step in T9SS transport.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41564-024-01644-7

Authors


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Institution:
University of Oxford
Division:
MSD
Department:
Biochemistry
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MSD
Department:
Pathology Dunn School
Role:
Author
ORCID:
0000-0001-8811-9871
More by this author
Institution:
University of Oxford
Division:
MSD
Department:
Biochemistry
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MSD
Department:
Biochemistry
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Role:
Author


Publisher:
Springer Nature
Journal:
Nature Microbiology More from this journal
Volume:
9
Issue:
4
Pages:
1089–1102
Publication date:
2024-03-27
Acceptance date:
2024-02-19
DOI:
EISSN:
2058-5276


Language:
English
Keywords:
Pubs id:
1620406
Local pid:
pubs:1620406
Deposit date:
2024-02-19

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