Secretion system

A protein-containing complex that serves as a channel for the secretion of curli. Curli are a fibers that serve as a major component of the extracellular matrix of pellicle biofilms.

A Mycobacterium smegmatis ESX-3 type VII secretion inner-membrane core complex in which EccB3, EccC3, EccD3, and EccE3 assemble into a dimeric membrane-embedded secretion machine.

A mycobacterial ESX-5 type VII secretion inner-membrane complex in which EccB5, EccC5, EccD5, EccE5, and MycP5 assemble into a multi-megadalton nanomachine that exports Esx and PE/PPE-family protein substrates.

An Escherichia coli Sec-pathway plasma-membrane holo-translocon complex in which SecY, SecE, SecG, SecD, SecF, YajC, and YidC assemble as a heteroheptamer that supports protein secretion and membrane-protein insertion.

A bacterial cytoplasmic-membrane Sec-pathway protein-conducting channel built from SecY, SecE, and SecG, through which unfolded secretory proteins or nascent membrane proteins move during translocation or membrane insertion.

A heterooligomeric protein complex that spans the bacterial periplasm and enables the secretion of adhesin proteins in Gram-negative bacteria. In Citrobacter rodentium, Salmonella enterica and Escherichia coli, the TAM complex consists of an Omp85-family protein, TamA, in the outer membrane and TamB in the inner membrane.

A complex of three proteins integral to the cytoplasmic membrane of bacteria and membranes of organelles derived from bacteria (chloroplasts and mitochondria) involved in membrane transport of folded proteins.

A Gram-negative bacterial trans-envelope protein secretion complex in which an inner-membrane ABC transporter and membrane-fusion protein recruit a TolC-like outer-membrane channel for one-step export of C-terminal-signal substrates.

A Gram-negative bacterial envelope-spanning secretion complex in which an inner-membrane platform and ATPase drive pseudopilus-mediated export of folded periplasmic substrates through an outer-membrane secretin.

The injectisome: a syringe-like envelope-spanning machine that delivers effector proteins from the bacterial cytoplasm directly into a eukaryotic host cell. Rings in the inner and outer membranes surround an export apparatus; an extracellular needle carries the secretion channel to a translocon pore in the host membrane. It is evolutionarily related to the flagellar export apparatus.

A bacterial envelope-spanning secretion complex related to conjugation machines that uses VirB-family channel, pilus, ATPase and coupling-protein subassemblies to translocate DNA and protein substrates.

A Bacteroidota trans-envelope secretion nanomachine that couples an inner-membrane PorL/PorM-family motor to PorK/PorN outer-membrane rings and a SprA/Sov translocon to export folded C-terminal-domain-bearing proteins across the outer membrane.

A complex of proteins that permits the translocation of proteins across the outer membrane via a transmembrane pore, formed by a beta-barrel, into the extracellular milieu or directly into host cells; the secreted proteins contain all the information required for translocation of an effector molecule through the cell envelope. The type V secretion systems includes the autotransporters (type Va), the two-partner secretion system (type Vb) and the Oca family (type Vc).

A bacterial contractile injection machine whose envelope-spanning membrane complex anchors a baseplate and sheath-wrapped Hcp tube; sheath contraction propels the Hcp/VgrG/PAAR spike and associated effectors out of the cell into target cells.

A bacterial type VI secretion system subassembly in which TssE-, TssF-, TssG-, and TssK-family proteins form a phage-baseplate-like platform that docks to the TssJ/TssL/TssM membrane complex and initiates Hcp tube and contractile-sheath assembly.

A bacterial type VI secretion system subassembly in which TssB/VipA- and TssC/VipB-family proteins polymerize into a metastable sheath around the Hcp tube and contract to drive Hcp/VgrG/PAAR spike ejection.

A bacterial type VI secretion system tail-tube subassembly in which Hcp-family proteins stack into hexameric rings that form the inner tube expelled by contractile-sheath firing.

A bacterial type VI secretion system subassembly in which TssJ-, TssL-, and TssM-family proteins form an envelope-spanning membrane core of the secretion apparatus.

A bacterial type VI secretion system tip subassembly in which trimeric VgrG proteins cap the Hcp tube and associate with PAAR-repeat proteins to sharpen the puncturing spike.