Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Crystals of SctV from different species reveal variable symmetry for the cytosolic domain of the type III secretion system export gate.

ABSTRACT: Type III secretion systems (T3SSs) are proteinaceous devices employed by Gram-negative bacteria to directly transport proteins into a host cell. Substrate recognition and secretion are strictly regulated by the export apparatus of the so-called injectisome. The export gate SctV engages chaperone-bound substrates of the T3SS in its nonameric cytoplasmic domain. Here, the purification and crystallization of the cytoplasmic domains of SctV from Photorhabdus luminescens (LscV_C) and Aeromonas hydrophila (AscV_C) are reported. Self-rotation functions revealed that LscV_C forms oligomers with either eightfold or ninefold symmetry in two different crystal forms. Similarly, AscV_C was found to exhibit tenfold rotational symmetry. These are the first instances of SctV proteins forming non-nonameric oligomers.

SUBMITTER: Gilzer D

PROVIDER: S-EPMC9629515 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Crystals of SctV from different species reveal variable symmetry for the cytosolic domain of the type III secretion system export gate.

Gilzer Dominic D Baum Eileen E Lieske Nele N Kowal Julia L JL Niemann Hartmut H HH

Acta crystallographica. Section F, Structural biology communications 20221014 Pt 11

Type III secretion systems (T3SSs) are proteinaceous devices employed by Gram-negative bacteria to directly transport proteins into a host cell. Substrate recognition and secretion are strictly regulated by the export apparatus of the so-called injectisome. The export gate SctV engages chaperone-bound substrates of the T3SS in its nonameric cytoplasmic domain. Here, the purification and crystallization of the cytoplasmic domains of SctV from Photorhabdus luminescens (LscV<sub>C</sub>) and Aeromo ...[more]

PMID: 36322424

Similar Datasets

Direct interaction of a chaperone-bound type III secretion substrate with the export gate.

Project description:Several gram-negative bacteria employ type III secretion systems (T3SS) to inject effector proteins into eukaryotic host cells directly from the bacterial cytoplasm. The export gate SctV (YscV in Yersinia) binds substrate:chaperone complexes such as YscX:YscY, which are essential for formation of a functional T3SS. Here, we present structures of the YscX:YscY complex alone and bound to nonameric YscV. YscX binds its chaperone YscY at two distinct sites, resembling the heterotrimeric complex of the T3SS needle subunit with its chaperone and co-chaperone. In the ternary complex the YscX N-terminus, which mediates YscX secretion, occupies a binding site within one YscV that is also used by flagellar chaperones, suggesting the interaction's importance for substrate recognition. The YscX C-terminus inserts between protomers of the YscV ring where the stalk protein binds to couple YscV to the T3SS ATPase. This primary YscV-YscX interaction is essential for the formation of a secretion-competent T3SS.

| S-EPMC9163089 | biostudies-literature

The Structure of an Injectisome Export Gate Demonstrates Conservation of Architecture in the Core Export Gate between Flagellar and Virulence Type III Secretion Systems.

Project description:Export of proteins through type III secretion systems (T3SS) is critical for motility and virulence of many major bacterial pathogens. Proteins are exported through a genetically defined export gate complex consisting of three proteins. We have recently shown at 4.2 Å that the flagellar complex of these three putative membrane proteins (FliPQR in flagellar systems, SctRST in virulence systems) assembles into an extramembrane helical assembly that likely seeds correct assembly of the rod. Here we present the structure of an equivalent complex from the Shigella virulence system at 3.5 Å by cryo-electron microscopy. This higher-resolution structure yields a more precise description of the structure and confirms the prediction of structural conservation in this core complex. Analysis of particle heterogeneity also suggests how the SctS/FliQ subunits sequentially assemble in the complex.IMPORTANCE Although predicted on the basis of sequence conservation, the work presented here formally demonstrates that all classes of type III secretion systems, flagellar or virulence, share the same architecture at the level of the core structures. This absolute conservation of the unusual extramembrane structure of the core export gate complex now allows work to move to focusing on both mechanistic studies of type III but also on fundamental studies of how such a complex is assembled.

| S-EPMC6593402 | biostudies-literature

"The structure of the Type III secretion system export gate with CdsO, an ATPase lever arm".

Project description:Type III protein secretion systems (T3SS) deliver effector proteins from the Gram-negative bacterial cytoplasm into a eukaryotic host cell through a syringe-like, multi-protein nanomachine. Cytosolic components of T3SS include a portion of the export apparatus, which traverses the inner membrane and features the opening of the secretion channel, and the sorting complex for substrate recognition and for providing the energetics required for protein secretion. Two components critical for efficient effector export are the export gate protein and the ATPase, which are proposed to be linked by the central stalk protein of the ATPase. We present the structure of the soluble export gate homo-nonamer, CdsV, in complex with the central stalk protein, CdsO, of its cognate ATPase, both derived from Chlamydia pneumoniae. This structure defines the interface between these essential T3S proteins and reveals that CdsO engages the periphery of the export gate that may allow the ATPase to catalyze an opening between export gate subunits to allow cargo to enter the export apparatus. We also demonstrate through structure-based mutagenesis of the homologous export gate in Pseudomonas aeruginosa that mutation of this interface disrupts effector secretion. These results provide novel insights into the molecular mechanisms governing active substrate recognition and translocation through a T3SS.

| S-EPMC7584215 | biostudies-literature

Structures of chaperone-substrate complexes docked onto the export gate in a type III secretion system.

Project description:The flagellum and the injectisome enable bacterial locomotion and pathogenesis, respectively. These nanomachines assemble and function using a type III secretion system (T3SS). Exported proteins are delivered to the export apparatus by dedicated cytoplasmic chaperones for their transport through the membrane. The structural and mechanistic basis of this process is poorly understood. Here we report the structures of two ternary complexes among flagellar chaperones (FliT and FliS), protein substrates (the filament-capping FliD and flagellin FliC), and the export gate platform protein FlhA. The substrates do not interact directly with FlhA; however, they are required to induce a binding-competent conformation to the chaperone that exposes the recognition motif featuring a highly conserved sequence recognized by FlhA. The structural data reveal the recognition signal in a class of T3SS proteins and provide new insight into the assembly of key protein complexes at the export gate.

| S-EPMC5932034 | biostudies-literature

The type III secretion chaperone SctY may shield the hydrophobic export gate-binding C-terminus of its substrate SctX.

Project description:Gram-negative bacteria such as Aeromonas and Yersinia spp. have developed mechanisms to inhibit the immune defense of their host. Effector proteins are directly injected into the host cytoplasm from the bacterial cytosol via type III secretion systems (T3SSs), where they modulate the cytoskeleton and signaling of the cell. Assembly of, and secretion via, T3SSs is tightly regulated by a number of bacterial proteins, including SctX (AscX in Aeromonas), the secretion of which is essential for T3SS function. Here, crystal structures of AscX in complex with SctY chaperones from Yersinia or Photorhabdus spp. carrying homologous T3SSs are described. There are crystal pathologies in all cases, with one crystal form diffracting anisotropically and the other two exhibiting strong pseudotranslation. The new structures reveal that the positioning of the substrate is very similar on different chaperones. However, the two C-terminal SctX helices that cap the N-terminal tetratricopeptide repeat of SctY shift and tilt depending on the identity of the chaperone. Moreover, the C-terminus of the α3 helix of AscX exhibits an unprecedented kink in two of the structures. In previous structures, the C-terminus of SctX protrudes beyond the chaperone as a straight helix: a conformation that is required for binding to the nonameric export gate SctV but that is unfavorable for binary SctX-SctY complexes due to the hydrophobicity of helix α3 of SctX. A kink in helix α3 may allow the chaperone to shield the hydrophobic C-terminus of SctX in solution.

| S-EPMC10233624 | biostudies-literature

Crystal structure of the C-terminal domain of the Salmonella type III secretion system export apparatus protein InvA.

Project description:InvA is a prominent inner-membrane component of the Salmonella type III secretion system (T3SS) apparatus, which is responsible for regulating virulence protein export in pathogenic bacteria. InvA is made up of an N-terminal integral membrane domain and a C-terminal cytoplasmic domain that is proposed to form part of a docking platform for the soluble export apparatus proteins notably the T3SS ATPase InvC. Here, we report the novel crystal structure of the C-terminal domain of Salmonella InvA which shows a compact structure composed of four subdomains. The overall structure is unique although the first and second subdomains exhibit structural similarity to the peripheral stalk of the A/V-type ATPase and a ring building motif found in other T3SS proteins respectively.

| S-EPMC2868250 | biostudies-literature

Functional Activation of the Flagellar Type III Secretion Export Apparatus.

Project description:Flagella are assembled sequentially from the inside-out with morphogenetic checkpoints that enforce the temporal order of subunit addition. Here we show that flagellar basal bodies fail to proceed to hook assembly at high frequency in the absence of the monotopic protein SwrB of Bacillus subtilis. Genetic suppressor analysis indicates that SwrB activates the flagellar type III secretion export apparatus by the membrane protein FliP. Furthermore, mutants defective in the flagellar C-ring phenocopy the absence of SwrB for reduced hook frequency and C-ring defects may be bypassed either by SwrB overexpression or by a gain-of-function allele in the polymerization domain of FliG. We conclude that SwrB enhances the probability that the flagellar basal body adopts a conformation proficient for secretion to ensure that rod and hook subunits are not secreted in the absence of a suitable platform on which to polymerize.

| S-EPMC4526659 | biostudies-literature

The substrate specificity switch FlhB assembles onto the export gate to regulate type three secretion.

Project description:Protein secretion through type-three secretion systems (T3SS) is critical for motility and virulence of many bacteria. Proteins are transported through an export gate containing three proteins (FliPQR in flagella, SctRST in virulence systems). A fourth essential T3SS protein (FlhB/SctU) functions to "switch" secretion substrate specificity once the growing hook/needle reach their determined length. Here, we present the cryo-electron microscopy structure of an export gate containing the switch protein from a Vibrio flagellar system at 3.2 Å resolution. The structure reveals that FlhB/SctU extends the helical export gate with its four predicted transmembrane helices wrapped around FliPQR/SctRST. The unusual topology of the FlhB/SctU helices creates a loop wrapped around the bottom of the closed export gate. Structure-informed mutagenesis suggests that this loop is critical in gating secretion and we propose that a series of conformational changes in the T3SS trigger opening of the gate through interactions between FlhB/SctU and FliPQR/SctRST.

| S-EPMC7064499 | biostudies-literature

Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus.

Project description:Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central "cup" substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation.

| S-EPMC5158082 | biostudies-literature

Engineering the Salmonella type III secretion system to export spider silk monomers.

Project description:The type III secretion system (T3SS) exports proteins from the cytoplasm, through both the inner and outer membranes, to the external environment. Here, a system is constructed to harness the T3SS encoded within Salmonella Pathogeneity Island 1 to export proteins of biotechnological interest. The system is composed of an operon containing the target protein fused to an N-terminal secretion tag and its cognate chaperone. Transcription is controlled by a genetic circuit that only turns on when the cell is actively secreting protein. The system is refined using a small human protein (DH domain) and demonstrated by exporting three silk monomers (ADF-1, -2, and -3), representative of different types of spider silk. Synthetic genes encoding silk monomers were designed to enhance genetic stability and codon usage, constructed by automated DNA synthesis, and cloned into the secretion control system. Secretion rates up to 1.8 mg l(-1) h(-1) are demonstrated with up to 14% of expressed protein secreted. This work introduces new parts to control protein secretion in Gram-negative bacteria, which will be broadly applicable to problems in biotechnology.

| S-EPMC2758716 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data