The inner rod of virulence-associated type III secretion systems constitutes a needle adapter of one helical turn that is deeply integrated into the system's export apparatus.

Autor: Torres-Vargas CE; Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Elfriede-Aulhorn-Str. 6, Tübingen, 72076, Germany., Kronenberger T; Department of Internal Medicine VIII, University Hospital Tübingen, Otfried-Müller-Str. 14, Tübingen, 72076, Germany.; School of Pharmacy, University of Eastern Finland, P.O. Box 1627, Kuopio, 70211, Finland., Roos N; Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Elfriede-Aulhorn-Str. 6, Tübingen, 72076, Germany., Dietsche T; Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Elfriede-Aulhorn-Str. 6, Tübingen, 72076, Germany., Poso A; Department of Internal Medicine VIII, University Hospital Tübingen, Otfried-Müller-Str. 14, Tübingen, 72076, Germany.; School of Pharmacy, University of Eastern Finland, P.O. Box 1627, Kuopio, 70211, Finland., Wagner S; Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Elfriede-Aulhorn-Str. 6, Tübingen, 72076, Germany.; Partner-Site Tübingen, German Center for Infection Research (DZIF), Elfriede-Aulhorn-Str. 6, Tübingen, 72076, Germany.
Jazyk: angličtina
Zdroj: Molecular microbiology [Mol Microbiol] 2019 Sep; Vol. 112 (3), pp. 918-931. Date of Electronic Publication: 2019 Jun 26.
DOI: 10.1111/mmi.14327
Abstrakt: Type III secretion injectisomes are essential virulence factors for many pathogenic bacteria by mediating the transport of effector proteins into eukaryotic host cells. The secretion conduit of injectisomes is formed by a helical assembly of three hydrophobic proteins (SctR, SctS and SctT), an inner rod (SctI) and a needle filament (SctF). SctI is thought to play a role in switching between the secretion of different substrate classes and assembly of the inner rod has been implicated in regulating the length of the needle filament. While high-resolution structures of the hydrophobic components and of the needle filament have been solved, little is known about the structure and the assembly of the inner rod, which impedes the deeper assessment of its function. Here we show by exhaustive in vivo photocrosslinking that SctI engages in extensive interactions with SctR and SctT throughout its entire length. Our data imply that the inner rod serves as an adapter between the export apparatus and the needle filament by forming one helical turn. We show that assembly of the inner rod does not play a role in needle length control nor in substrate specificity switching. Instead, our findings imply that inner rod assembly must precede assembly of the needle filament.
(© 2019 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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