A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly

Kinoshita, Miki; Miyata, Tomoko; Makino, Fumiaki; Imada, Katsumi; Namba, Keiichi; Minamino, Tohru

doi:https://doi.org/10.1073/pnas.2507221122

A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly

Kinoshita, Miki; Miyata, Tomoko; Makino, Fumiaki et al.

Proceedings of the National Academy of Sciences of the United States of America, 2025, 122(34), e2507221122

Number of Access:183（2026-02-02 19:51 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/103262

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Title	A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly
Creator	CreatorName Kinoshita, Miki
	NRID 1000030423156 1000030423156 researchmap permalink miya_t miya_t Scopus Author ID 7401764889 7401764889 ORCID 0000-0002-5543-7459 0000-0002-5543-7459 CreatorName Miyata, Tomoko
	CreatorName Makino, Fumiaki
	NRID 1000040346143 1000040346143 ORCID 0000-0003-1342-8885 0000-0003-1342-8885 researchmap permalink read0096832 read0096832 Scopus Author ID 7006628770 7006628770 CreatorName Imada, Katsumi
	NRID 1000030346142 1000030346142 ORCID 0000-0003-2911-5875 0000-0003-2911-5875 researchmap permalink read0096830 read0096830 Scopus Author ID 7103162863 7103162863 CreatorName Namba, Keiichi
	NRID 1000020402993 1000020402993 ORCID 0000-0002-8175-1951 0000-0002-8175-1951 researchmap permalink tohru_minamino tohru_minamino Scopus Author ID 7006391123 7006391123 CreatorName Minamino, Tohru
Subject	cryoelectron microscopy
	flagellar rod
	flagellum
	type III secretion system
Description	Kinoshita M., Miyata T., Makino F., et al. A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly. Proceedings of the National Academy of Sciences of the United States of America 122, e2507221122 (2025); https://doi.org/10.1073/pnas.2507221122.
Abstract	The FliPQR complex constitutes a channel for export of the flagellar proteins involved in axial structure assembly. It also serves as a template for the assembly of the rod structure, which consists of FliE, FlgB, FlgC, FlgF, and FlgG. FliP, FliQ, and FliR assemble into a right-handed helical structure within the central pore of the flagellar basal body MS-ring, and the complex has two gates on the cytoplasmic and periplasmic sides. The periplasmic gate, formed by the N-terminal α-helices of FliP and FliR, remains closed until six FliE subunits assemble onto FliP and FliR to form the first layer of the rod, but it has remained unclear how each FliE subunit opens the gate and assembles in the absence of the rod cap required for efficient assembly of other rod proteins. Here, we present a cryoelectron microscopy structure of the FliPQR complex in closed form at 3.0 Å resolution. A β-cap, formed by the N-terminal β-strands of FliP and FliR, is located at the top of the FliPQR complex and tightly seals the closed gate. The β-cap has a narrow pore that efficiently and accurately leads the first FliE subunit to its assembly site. Interactions of FliE with FliP and FliR induce a conformational change in FliP and FliR, with their N-terminal α-helices move up and outward to open the gate. Consequently, each of the N-terminal β-strands of FliP and FliR detaches from the β-cap one after another, thereby creating a docking site for the next FliE subunit to efficiently assemble.
Publisher	National Academy of Sciences
Source Title	Proceedings of the National Academy of Sciences of the United States of America
Volume (Issue)	122(34)
Page	e2507221122
Date of Issued	2025-08-20
Language	English
Handle URL	https://hdl.handle.net/11094/103262
PISSN	00278424
eISSN	10916490
Relation.isIdenticalTo	DOI (Publisher Version) https://doi.org/10.1073/pnas.2507221122
Access Rights	open access
CopyRight	This article is licensed under a Creative Commons Attribution 4.0 International License.
oaire:version	Version of Record
Category	学術雑誌論文 Journal Article

Resource Type	journal article
Local Type	Journal Article
DCMI Type	Text
DCTERMS.bibliographicCitation	Proceedings of the National Academy of Sciences of the United States of America. 2025, 122(34), p. e2507221122
DC.title	A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly
DC.creator	Kinoshita, Miki
	Miyata, Tomoko
	Makino, Fumiaki
	Imada, Katsumi
	Namba, Keiichi
	Minamino, Tohru
DC.publisher	National Academy of Sciences
DC.language' scheme='DCTERMS.RFC1766	English
DC.type' scheme='DCTERMS.DCMIType	Text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2025-08-20
DC.identifier	https://doi.org/10.1073/pnas.2507221122
DC.subject	cryoelectron microscopy
	flagellar rod
	flagellum
	type III secretion system
DC.description	Kinoshita M., Miyata T., Makino F., et al. A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly. Proceedings of the National Academy of Sciences of the United States of America 122, e2507221122 (2025); https://doi.org/10.1073/pnas.2507221122.
DCTERMS.abstract	The FliPQR complex constitutes a channel for export of the flagellar proteins involved in axial structure assembly. It also serves as a template for the assembly of the rod structure, which consists of FliE, FlgB, FlgC, FlgF, and FlgG. FliP, FliQ, and FliR assemble into a right-handed helical structure within the central pore of the flagellar basal body MS-ring, and the complex has two gates on the cytoplasmic and periplasmic sides. The periplasmic gate, formed by the N-terminal α-helices of FliP and FliR, remains closed until six FliE subunits assemble onto FliP and FliR to form the first layer of the rod, but it has remained unclear how each FliE subunit opens the gate and assembles in the absence of the rod cap required for efficient assembly of other rod proteins. Here, we present a cryoelectron microscopy structure of the FliPQR complex in closed form at 3.0 Å resolution. A β-cap, formed by the N-terminal β-strands of FliP and FliR, is located at the top of the FliPQR complex and tightly seals the closed gate. The β-cap has a narrow pore that efficiently and accurately leads the first FliE subunit to its assembly site. Interactions of FliE with FliP and FliR induce a conformational change in FliP and FliR, with their N-terminal α-helices move up and outward to open the gate. Consequently, each of the N-terminal β-strands of FliP and FliR detaches from the β-cap one after another, thereby creating a docking site for the next FliE subunit to efficiently assemble.
DC.rights	This article is licensed under a Creative Commons Attribution 4.0 International License.
DC.format	103262
citation_title	A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly
citation_author	Kinoshita, Miki
	Miyata, Tomoko
	Makino, Fumiaki
	Imada, Katsumi
	Namba, Keiichi
	Minamino, Tohru
citation_publisher	National Academy of Sciences
citation_language	English
citation_date	2025-08-20
citation_journal_title	Proceedings of the National Academy of Sciences of the United States of America
citation_volume	122
citation_issue	34
citation_firstpage	e2507221122
citation_doi	https://doi.org/10.1073/pnas.2507221122
citation_public_url	https://hdl.handle.net/11094/103262

A β-cap on the FliPQR protein-export channel acts as the cap for initial flagellar rod assembly

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