Bacterial type II secretion

A species-neutral module for export of folded proteins from the periplasm across the outer membrane by the type II secretion system. A multiprotein inner-membrane platform recruits the secretion ATPase and supports assembly of a dynamic pseudopilus, which displaces substrates through an oligomeric outer-membrane secretin. Delivery of substrates into the periplasm by Sec or Tat, substrate folding, and unrelated fimbrial or pilus systems are outside this module.

MODULE:bacterial_type_ii_secretionDRAFTBiological Processmodules/bacterial_type_ii_secretion.yaml
protein secretion by the type II secretion systemGO:0015628
GO:0015628
protein secretion by the type II secretion system
GO:0015628 defines the biological process modeled by the reusable module.
GO:0015627
type II protein secretion system complex
GO:0015627 identifies the complete envelope-spanning secretion machinery represented by the four module parts.
KEGG:ppu03070
KEGG bacterial secretion system
The broad KEGG map contains multiple secretion routes; only its canonical Xcp/Gsp type II branch is instantiated here.
file:projects/P_PUTIDA/deep-research/PSEPK__bacterial_type_ii_secretion__ppu03070-deep-research-openscientist.md
OpenScientist PSEPK ppu03070 satisfiability review
The species/pathway/taxon report was used to distinguish the Xcp/Gsp branch from Sec, Tat, type I, type VI, TPS, and fimbrial candidates on the broad map.
file:projects/P_PUTIDA/batches/ppu03070_bacterial_type_ii_secretion.tsv
PSEPK ppu03070 type II secretion batch
The batch table records the exact twelve-protein Xcp/Gsp implementation and links each protein to its focused gene review.

Reusable boundary: the module begins with the assembled type II secretion machine acting on folded periplasmic substrates and ends with passage through the outer-membrane secretin. Sec and Tat are upstream substrate-delivery routes, not parts of this module. Type IV pili share homologous ATPase, platform, prepilin, and secretin folds but are distinct surface structures; unrelated fimbrial proteins must not be admitted solely from shared domains. GspN-like proteins are lineage-variable accessory factors and are not forced into the conserved four-part core.

5Nodes
4Parts
0Variant Sets
0Variants
13Annotons
3Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:bacterial_type_ii_secretion deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Function consistency and core coverage

8 gene-function check(s) reflected in core functions · 0 conflict(s) · 7 evidence or coverage gap(s) (15 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

AnnotonParticipantFunctionAssessment
gspe_motor GspE exemplar
UniProtKB:Q88P06
Family Representative 		ATP hydrolysis activity
GO:0016887 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gspe_motor Pseudomonas aeruginosa XcpR cross-species exemplar
UniProtKB:Q00512
Family Representative 		ATP hydrolysis activity
GO:0016887 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pild_leader_peptidase PilD exemplar
UniProtKB:Q88Q64
Family Representative 		aspartic-type endopeptidase activity
GO:0004190 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pild_leader_peptidase Pseudomonas aeruginosa PilD cross-species exemplar
UniProtKB:P22610
Family Representative 		aspartic-type endopeptidase activity
GO:0004190 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pild_n_methyltransferase PilD exemplar
UniProtKB:Q88Q64
Family Representative 		N-terminal protein N-methyltransferase activity
GO:0071885 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
pild_n_methyltransferase Pseudomonas aeruginosa PilD cross-species exemplar
UniProtKB:P22610
Family Representative 		N-terminal protein N-methyltransferase activity
GO:0071885 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gspg_major_pseudopilin GspG exemplar
UniProtKB:Q88P04
Family Representative 		structural molecule activity
GO:0005198 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gspg_major_pseudopilin Pseudomonas aeruginosa XcpT cross-species exemplar
UniProtKB:Q00514
Family Representative 		structural molecule activity
GO:0005198 		Review Missing
No ai-review exists for this protein; its function and core-function coverage cannot yet be checked.
gspd_secretin XcpQ exemplar
UniProtKB:Q88P07
Family Representative 		protein transmembrane transporter activity
GO:0008320 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gspd_secretin Pseudomonas aeruginosa XcpQ cross-species exemplar
UniProtKB:P35818
Family Representative 		protein transmembrane transporter activity
GO:0008320 		Function Unreviewed
No retained annotation or core molecular function supports this GO assertion. Missing or broader evidence is a coverage gap, not proof the activity is absent.
gspe_motor GspE family
InterPro:IPR054757
Family 		ATP hydrolysis activity
GO:0016887 		Family Review Missing
No supported structured family review is available for InterPro:IPR054757.
pild_leader_peptidase prepilin leader peptidase/N-methyltransferase family
PANTHER:PTHR30487
Family 		aspartic-type endopeptidase activity
GO:0004190 		Family Review Missing
No supported structured family review is available for PANTHER:PTHR30487.
pild_n_methyltransferase prepilin leader peptidase/N-methyltransferase family
PANTHER:PTHR30487
Family 		N-terminal protein N-methyltransferase activity
GO:0071885 		Family Review Missing
No supported structured family review is available for PANTHER:PTHR30487.
gspg_major_pseudopilin GspG major pseudopilin family
PANTHER:PTHR30093:SF44
Family 		structural molecule activity
GO:0005198 		Family Review Missing
No supported structured family review is available for PANTHER:PTHR30093:SF44.
gspd_secretin GspD secretin family
InterPro:IPR013356
Family 		protein transmembrane transporter activity
GO:0008320 		Family Review Missing
No supported structured family review is available for InterPro:IPR013356.

Gene-review completeness (19/24 grounded genes reviewed)

19 complete review(s) · 0 with deep research · 5 missing review · 19 reviewed but lacking deep research

Gene Review Complete Deep research
gspE Q88P06 ✓ ✓ ✗
gspF Q88P05 ✓ ✓ ✗
gspG Q88P04 ✓ ✓ ✗
Klebsiella PulC cross-species exemplar P15643 ✗ — —
Pseudomonas aeruginosa XcpY cross-species exemplar P25060 ✗ — —
Pseudomonas aeruginosa XcpZ cross-species exemplar P25061 ✗ — —
pilD P22610 ✓ ✓ ✗
pilD Q88Q64 ✓ ✓ ✗
Pseudomonas aeruginosa XcpT cross-species exemplar Q00514 ✗ — —
Pseudomonas aeruginosa XcpU cross-species exemplar Q00515 ✗ — —
xcpP Q88P08 ✓ ✓ ✗
xcpQ P35818 ✓ ✓ ✗
xcpQ Q88P07 ✓ ✓ ✗
xcpR Q00512 ✓ ✓ ✗
xcpS Q00513 ✓ ✓ ✗
xcpU Q88P03 ✓ ✓ ✗
xcpV Q00516 ✓ ✓ ✗
xcpV Q88P02 ✓ ✓ ✗
xcpW Q00517 ✓ ✓ ✗
xcpW Q88P01 ✓ ✓ ✗
xcpX Q00518 ✓ ✓ ✗
xcpX Q88P11 ✓ ✓ ✗
xcpY Q88P00 ✓ ✓ ✗
xcpZ Q88NZ9 ✓ ✓ ✗

Details

Context
bacteriaNCBITaxon:2
Bacterial type II secretionBiological Processbacterial_type_ii_secretion
protein secretion by the type II secretion systemGO:0015628
Context
bacteriaNCBITaxon:2

Connections

inner_membrane_platform -> pseudopilus Provides Input For
pseudopilus -> outer_membrane_secretin Provides Input For
Part 1: Coordinate the motor, pseudopilus, and secretin at the inner membrane
Type II secretion inner-membrane platformProtein Complexinner_membrane_platform

The GspC/F/L/M platform spans the inner membrane, recruits the GspE motor, and couples pseudopilus assembly to the outer-membrane secretin.

Annotons

GspC envelope connector
gspc_connector
Participant: Family: GspC/XcpP family
Family:
GspC/XcpP family
Representative Members: XcpP exemplarUniProtKB:Q88P08 Klebsiella PulC cross-species exemplarUniProtKB:P15643

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Couples the inner-membrane platform to the outer-membrane secretin.

file:PSEPK/xcpP/xcpP-ai-review.yaml
The focused review identifies Q88P08 as the GspC-equivalent connector in the Xcp machine.
GspF platform core
gspf_platform_core
Participant: Family: GspF family
Family:
GspF familyInterPro:IPR011850
Representative Members: GspF exemplarUniProtKB:Q88P05 Pseudomonas aeruginosa XcpS cross-species exemplarUniProtKB:Q00513

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Forms the central polytopic membrane-platform subunit.

file:PSEPK/gspF/gspF-ai-review.yaml
The focused review accepts inner-membrane, T2SS-complex, and T2SS-process annotations for Q88P05.
GspL ATPase-facing platform subunit
gspl_atpase_receptor
Participant: Family: GspL family
Family:
GspL familyInterPro:IPR025691
Representative Members: XcpY exemplarUniProtKB:Q88P00 Pseudomonas aeruginosa XcpY cross-species exemplarUniProtKB:P25060

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Recruits and positions the secretion ATPase at the membrane platform.

file:PSEPK/xcpY/xcpY-ai-review.yaml
The focused review grounds Q88P00 as the GspL-family ATPase-facing platform subunit.
GspM platform stabilizer
gspm_platform_stabilizer
Participant: Family: GspM family
Family:
GspM familyInterPro:IPR030927
Representative Members: XcpZ exemplarUniProtKB:Q88NZ9 Pseudomonas aeruginosa XcpZ cross-species exemplarUniProtKB:P25061

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Stabilizes the inner-membrane platform and its partner subunits.

file:PSEPK/xcpZ/xcpZ-ai-review.yaml
The focused review grounds Q88NZ9 as the GspM-family platform stabilizer.
Part 2: Hydrolyze ATP to energize pseudopilus assembly
Type II secretion ATPaseMolecular Functionsecretion_atpase

Annotons

GspE secretion ATPase
gspe_motor
Participant: Family: GspE family
Family:
GspE familyInterPro:IPR054757
Representative Members: GspE exemplarUniProtKB:Q88P06 Pseudomonas aeruginosa XcpR cross-species exemplarUniProtKB:Q00512

Function

ATP hydrolysis activityGO:0016887

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

ATP-hydrolyzing motor that powers pseudopilus assembly.

Part 3: Assemble the substrate-displacing pseudopilus
Type II secretion pseudopilusProtein Complexpseudopilus

PilD-dependent maturation, a major GspG pseudopilin polymer, and a minor GspH/I/J/K initiation or tip complex convert ATP-dependent assembly into substrate displacement.

Annotons

PilD prepilin leader peptidase
pild_leader_peptidase
Participant: Family: prepilin leader peptidase/N-methyltransferase family
Family:
prepilin leader peptidase/N-methyltransferase familyPANTHER:PTHR30487
Representative Members: PilD exemplarUniProtKB:Q88Q64 Pseudomonas aeruginosa PilD cross-species exemplarUniProtKB:P22610

Function

aspartic-type endopeptidase activityGO:0004190

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Removes short leader peptides from pseudopilin precursors.

file:PSEPK/pilD/pilD-ai-review.yaml
The focused review accepts leader-peptide cleavage as a core PilD activity required for pseudopilus maturation.
PilD prepilin N-methyltransferase
pild_n_methyltransferase
Participant: Family: prepilin leader peptidase/N-methyltransferase family
Family:
prepilin leader peptidase/N-methyltransferase familyPANTHER:PTHR30487
Representative Members: PilD exemplarUniProtKB:Q88Q64 Pseudomonas aeruginosa PilD cross-species exemplarUniProtKB:P22610

Function

N-terminal protein N-methyltransferase activityGO:0071885

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Methylates the newly exposed N terminus after leader cleavage.

file:PSEPK/pilD/pilD-ai-review.yaml
The focused review proposes the missing methyltransferase activity from the explicit UniProt functional statement.
GspG major pseudopilin
gspg_major_pseudopilin
Participant: Family: GspG major pseudopilin family
Family:
GspG major pseudopilin familyPANTHER:PTHR30093:SF44
Representative Members: GspG exemplarUniProtKB:Q88P04 Pseudomonas aeruginosa XcpT cross-species exemplarUniProtKB:Q00514

Function

structural molecule activityGO:0005198

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Polymerizes as the major structural subunit of the pseudopilus.

file:PSEPK/gspG/gspG-ai-review.yaml
The focused review distinguishes the exact GspG pseudopilin from unrelated type IV pilins.
GspH minor pseudopilin
gsph_minor_pseudopilin
Participant: Family: GspH family
Family:
GspH familyInterPro:IPR049875
Representative Members: XcpU exemplarUniProtKB:Q88P03 Pseudomonas aeruginosa XcpU cross-species exemplarUniProtKB:Q00515

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Contributes to the minor-pseudopilin initiation or tip assembly.

file:PSEPK/xcpU/xcpU-ai-review.yaml
The focused review grounds Q88P03 with its GspH-specific InterPro domain.
GspI minor pseudopilin
gspi_minor_pseudopilin
Participant: Family: GspI family
Family:
GspI familyPANTHER:PTHR38779
Representative Members: XcpV exemplarUniProtKB:Q88P02 Pseudomonas aeruginosa XcpV cross-species exemplarUniProtKB:Q00516

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Contributes to the minor-pseudopilin initiation or tip assembly.

file:PSEPK/xcpV/xcpV-ai-review.yaml
The focused review accepts Q88P02 as a GspI-family minor pseudopilin.
GspJ minor pseudopilin
gspj_minor_pseudopilin
Participant: Family: GspJ/XcpW family
Family:
GspJ/XcpW family
Representative Members: XcpW exemplarUniProtKB:Q88P01 Pseudomonas aeruginosa XcpW cross-species exemplarUniProtKB:Q00517

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Contributes to the minor-pseudopilin initiation or tip assembly.

file:PSEPK/xcpW/xcpW-ai-review.yaml
The focused review grounds Q88P01 as the XcpW/GspJ-equivalent minor pseudopilin.
GspK minor pseudopilin
gspk_minor_pseudopilin
Participant: Family: GspK family
Family:
GspK familyPANTHER:PTHR38831
Representative Members: XcpX exemplarUniProtKB:Q88P11 Pseudomonas aeruginosa XcpX cross-species exemplarUniProtKB:Q00518

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

plasma membraneGO:0005886

Caps or stabilizes the minor-pseudopilin tip assembly.

file:PSEPK/xcpX/xcpX-ai-review.yaml
The focused review grounds Q88P11 in the GspK-specific PANTHER family.
Part 4: Provide the gated outer-membrane exit for folded substrates
Type II secretion outer-membrane secretinProtein Complexouter_membrane_secretin

Annotons

GspD outer-membrane secretin
gspd_secretin
Participant: Family: GspD secretin family
Family:
GspD secretin familyInterPro:IPR013356
Representative Members: XcpQ exemplarUniProtKB:Q88P07 Pseudomonas aeruginosa XcpQ cross-species exemplarUniProtKB:P35818

Function

protein transmembrane transporter activityGO:0008320

Processes

protein secretion by the type II secretion systemGO:0015628

Locations

cell outer membraneGO:0009279

Oligomerizes into the outer-membrane secretin used for substrate passage.

file:PSEPK/xcpQ/xcpQ-ai-review.yaml
The focused review accepts the GspD secretin, T2SS-complex, T2SS-process, and outer-membrane assignments for Q88P07.