Insights into type IX secretion from PorKN cogwheel structure bound to PorG and attachment complexes
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
View abstract on PubMed
Summary
This summary is machine-generated.The Type IX Secretion System in Bacteroidota bacteria uses a novel cogwheel-like mechanism. This involves PorKN rings, PorLM motors, and PorG interaction for protein export across the outer membrane.
Area Of Science
- Microbiology
- Structural Biology
- Bacterial Physiology
Background
- The Type IX Secretion System (T9SS) is crucial for protein export across the outer membrane in Bacteroidota.
- The precise molecular mechanisms governing T9SS function remain largely unelucidated.
- Key components include the Sov translocon, Attachment Complexes (PorQ, U, V, Z), PorLM motors, and PorKN rings.
Purpose Of The Study
- To elucidate the structural basis and mechanistic details of the Type IX Secretion System in Porphyromonas gingivalis.
- To determine the structure of the periplasmic PorKN rings and their interaction with other T9SS components.
Main Methods
- Cryo-electron microscopy (cryo-EM) at ~3.5 Å resolution.
- Biochemical analysis to identify critical disulfide bonds.
- Localization studies of Attachment Complexes.
Main Results
- A high-resolution cryo-EM structure of the PorKN periplasmic rings (32-33 subunits each) was determined.
- A critical disulfide bond between PorK and the outer membrane protein PorG was identified, essential for secretion.
- Attachment Complexes were shown to bind above the PorKN rings.
Conclusions
- The PorKN rings function as a cogwheel, with PorN projections engaging the PorLM motor.
- This interaction drives the rotation of the PorKN-PorG complex, powering protein secretion.
- The system facilitates both protein export and coordinated cell surface attachment of secreted cargo.
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
Related Concept Videos
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...