Podovirus short-tail assembly, receptor-triggered nozzle remodeling, and internal core protein DNA-ejectosome channel formation

A coordinated morphogenetic and host-entry module characteristic of T7-like podoviruses (Autographiviridae and related short-tailed Caudoviricetes) that solves the topological challenge of translocating a double-stranded DNA genome across the Gram-negative outer membrane, peptidoglycan cell wall, periplasm, and inner membrane using a non-contractile tail shorter than the cell envelope thickness. During procapsid assembly, a cylindrical internal core stack of gp14, gp15, and the lytic transglycosylase gp16 is assembled coaxially atop the dodecameric portal ring (gp8) inside the capsid. Following DNA packaging, the dodecameric gatekeeper adaptor (gp11), hexameric tail nozzle (gp12), tail assembly protein (gp7.3), and six trimeric tail fibers (gp17) assemble onto the portal vertex. Upon irreversible lipopolysaccharide receptor engagement and tail fiber reorientation, conformational opening of the gp12 nozzle gates the sequential ejection of gp14 (forming the outer membrane pore), gp16 (locally hydrolyzing periplasmic peptidoglycan via its N-terminal lytic transglycosylase domain and spanning the inner membrane), and gp15 (forming a hexameric periplasmic tunnel with gp16) to construct a continuous trans-envelope DNA-ejectosome conduit into the host cytoplasm.

MODULE:phage_podovirus_short_tail_ejectionCOMPLETECONCRETEBiological Processmodules/phage_podovirus_short_tail_ejection.yaml
viral tail assemblyGO:0098003 adhesion receptor-mediated virion attachment to host cellGO:0098671 symbiont entry into host cell via disruption of host cell wall peptidoglycanGO:0098932 symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002
PMID:23884409
Structural characterization of the bacteriophage T7 tail machinery.
Defines the architecture and stoichiometric assembly of the T7 portal (gp8), adaptor (gp11), nozzle (gp12), and tail fiber (gp17) complex.
PMID:23306440
The bacteriophage t7 virion undergoes extensive structural remodeling during infection.
Cryo-electron tomography demonstrating ejection of the internal core proteins gp14, gp15, and gp16 upon receptor binding to form an extended trans-envelope tail conduit across the Escherichia coli cell envelope.
PMID:34214465
Cryo-EM structure of the periplasmic tunnel of T7 DNA-ejectosome at 2.7 Å resolution.
Atomic-resolution cryo-EM structure of the gp15-gp16 periplasmic tunnel of the T7 DNA-ejectosome spanning the periplasm and peptidoglycan layer.
PMID:22645347
Structure of the receptor-binding carboxy-terminal domain of bacteriophage T7 tail fibers.
Establishes the trimeric pyramid structure and lipopolysaccharide-binding loops of the T7 gp17 tail fiber C-terminal receptor-binding domain.
GO:0099002
symbiont genome ejection through host cell envelope, short tail mechanism
Defines the biological process of viral genome delivery across the bacterial envelope via a short non-contractile podovirus tail and extensible internal core ejectosome.

Exemplar phage: Escherichia phage T7 (NCBITaxon:10760). Generalizes across Autographiviridae and other podoviruses (such as coliphage T3, Klebsiella phage KP32, Pseudomonas phage phiKMV, and cyanophage P-SSP7) that couple a gp11/gp12-type short tubular nozzle to an internal virion core (gp14/gp15/gp16 orthologs) ejected to form a transient trans-envelope DNA channel.

4Nodes
3Parts
0Variant Sets
0Variants
8Annotons
3Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:phage_podovirus_short_tail_ejection 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) · 8 evidence or coverage gap(s) (16 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
gp8_portal_vertex_activity 8 (Escherichia phage T7)
UniProtKB:P03728
Family Representative 		structural constituent of virion
GO:0039660 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp14_outer_membrane_core_activity 14 (Escherichia phage T7)
UniProtKB:P03724
Family Representative 		pore-forming activity
GO:0140911 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp15_periplasmic_tunnel_core_activity 15 (Escherichia phage T7)
UniProtKB:P03725
Family Representative 		DNA binding
GO:0003677 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp16_transglycosylase_ejectosome_activity 16 (Escherichia phage T7)
UniProtKB:P03726
Family Representative 		lytic exotransglycosylase activity
GO:0140100 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp11_adaptor_ring_activity 11 (Escherichia phage T7)
UniProtKB:P03746
Family Representative 		structural constituent of virion
GO:0039660 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp12_nozzle_valve_activity 12 (Escherichia phage T7)
UniProtKB:P03747
Family Representative 		structural constituent of virion
GO:0039660 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp7_3_tail_tip_assembly_activity 7.3 (Escherichia phage T7)
UniProtKB:P03751
Family Representative 		structural constituent of virion
GO:0039660 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp17_tail_fiber_receptor_binding 17 (Escherichia phage T7)
UniProtKB:P03748
Family Representative 		structural constituent of virion
GO:0039660 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gp8_portal_vertex_activity Podovirus head-tail connector portal family
Family 		structural constituent of virion
GO:0039660 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp14_outer_membrane_core_activity Phage T7 internal virion protein gp14 family
Family 		pore-forming activity
GO:0140911 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp15_periplasmic_tunnel_core_activity Phage T7 internal virion protein gp15 family
Family 		DNA binding
GO:0003677 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp16_transglycosylase_ejectosome_activity Phage T7 internal virion transglycosylase gp16 family
Family 		lytic exotransglycosylase activity
GO:0140100 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp11_adaptor_ring_activity Podovirus tail adaptor gp11 family
Family 		structural constituent of virion
GO:0039660 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp12_nozzle_valve_activity Podovirus tail nozzle gp12 family
Family 		structural constituent of virion
GO:0039660 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp7_3_tail_tip_assembly_activity Phage T7-like virion assembly protein gp7.3 family
Family 		structural constituent of virion
GO:0039660 		Family Id Missing
The family has no identifier linking it to a curated family review.
gp17_tail_fiber_receptor_binding Phage T7 tail fiber protein gp17 family
Family 		structural constituent of virion
GO:0039660 		Family Id Missing
The family has no identifier linking it to a curated family review.

Gene-review completeness (8/8 grounded genes reviewed)

8 complete review(s) · 0 with deep research · 0 missing review · 8 reviewed but lacking deep research

Gene Review Complete Deep research
11 P03746 ✓ ✓ ✗
12 P03747 ✓ ✓ ✗
14 P03724 ✓ ✓ ✗
15 P03725 ✓ ✓ ✗
16 P03726 ✓ ✓ ✗
17 P03748 ✓ ✓ ✗
7.3 P03751 ✓ ✓ ✗
8 P03728 ✓ ✓ ✗

Details

Context
CaudoviricetesNCBITaxon:2731619 Escherichia phage T7NCBITaxon:10760
Podovirus short-tail assembly and internal core DNA-ejectosome channel formationBiological Processphage_podovirus_short_tail_ejection
viral tail assemblyGO:0098003 adhesion receptor-mediated virion attachment to host cellGO:0098671 symbiont entry into host cell via disruption of host cell wall peptidoglycanGO:0098932 symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002
Context
CaudoviricetesNCBITaxon:2731619 Escherichia phage T7NCBITaxon:10760

Connections

Part 1: portal vertex and internal core stack assembly
Co-assembly of the dodecameric portal ring (gp8) and internal core cylinder (gp14-gp15-gp16)Protein Complexportal_and_internal_core_assembly_step

Annotons

Portal protein gp8
gp8_portal_vertex_activity
Participant: Family: Podovirus head-tail connector portal family
Family:
Podovirus head-tail connector portal family
Representative Members: 8 (Escherichia phage T7)UniProtKB:P03728

Function

structural constituent of virionGO:0039660

Processes

viral capsid assemblyGO:0019069 viral DNA genome packagingGO:0019073

Locations

host cell cytoplasmGO:0030430

Forms the 12-subunit portal ring at the unique fivefold vertex of the T7 procapsid, serving both as the conduit for terminase-driven DNA packaging and DNA ejection and as the internal platform on which the coaxial gp14-gp15-gp16 core cylinder is assembled.

Internal virion protein gp14
gp14_outer_membrane_core_activity
Participant: Family: Phage T7 internal virion protein gp14 family
Family:
Phage T7 internal virion protein gp14 family
Representative Members: 14 (Escherichia phage T7)UniProtKB:P03724

Function

pore-forming activityGO:0140911

Processes

symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002

Locations

host outer membraneGO:0044384

Forms the base ring of the internal core stack directly above the gp8 portal crown (~12 copies) and is the first internal core protein ejected upon infection to partition into the host cell envelope and anchor the outer membrane pore of the DNA-ejectosome.

Internal virion protein gp15
gp15_periplasmic_tunnel_core_activity
Participant: Family: Phage T7 internal virion protein gp15 family
Family:
Phage T7 internal virion protein gp15 family
Representative Members: 15 (Escherichia phage T7)UniProtKB:P03725

Function

DNA bindingGO:0003677

Processes

symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002

Locations

host cell periplasmic spaceGO:0044229

Forms the middle tier of the internal virion core (8-fold in the virion) that refolds upon ejection into a hexameric periplasmic tunnel complexed with gp16, bridging the outer membrane pore to the inner membrane DNA channel.

Peptidoglycan transglycosylase gp16
gp16_transglycosylase_ejectosome_activity
Participant: Family: Phage T7 internal virion transglycosylase gp16 family
Family:
Phage T7 internal virion transglycosylase gp16 family
Representative Members: 16 (Escherichia phage T7)UniProtKB:P03726

Function

lytic exotransglycosylase activityGO:0140100

Processes

symbiont entry into host cell via disruption of host cell wall peptidoglycanGO:0098932 symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002

Locations

host cell plasma membraneGO:0020002

Forms the apical tier of the internal core cylinder inside the capsid and, upon ejection, uses its N-terminal soluble lytic transglycosylase domain to locally cleave periplasmic peptidoglycan while its C-terminal domains co-assemble with gp15 and insert into the host inner membrane to translocate the leading end of the viral genome into the cytoplasm.

Part 2: short tubular tail adaptor and nozzle assembly
Post-packaging assembly of the gp11 adaptor, gp12 nozzle, and gp7.3 tail tip factorProtein Complexshort_tail_nozzle_assembly_step

Annotons

Tail tubular protein gp11
gp11_adaptor_ring_activity
Participant: Family: Podovirus tail adaptor gp11 family
Family:
Podovirus tail adaptor gp11 family
Representative Members: 11 (Escherichia phage T7)UniProtKB:P03746

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003 symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002

Locations

host cell cytoplasmGO:0030430

Assembles as a dodecameric adaptor ring onto the exposed outer clip of the gp8 portal after DNA packaging termination, sealing the packaged genome and providing the docking interface for the hexameric gp12 nozzle and six trimeric gp17 tail fibers.

Tail tubular protein gp12
gp12_nozzle_valve_activity
Participant: Family: Podovirus tail nozzle gp12 family
Family:
Podovirus tail nozzle gp12 family
Representative Members: 12 (Escherichia phage T7)UniProtKB:P03747

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003 symbiont genome ejection through host cell envelope, short tail mechanismGO:0099002

Locations

host cell cytoplasmGO:0030430

Forms the hexameric lower tail nozzle below the gp11 adaptor ring, acting as the closed distal valve in the mature virion that undergoes iris-like dilation upon receptor-triggered tail fiber reorientation to allow ejection of the internal core proteins and genomic DNA.

Tail assembly protein gp7.3
gp7_3_tail_tip_assembly_activity
Participant: Family: Phage T7-like virion assembly protein gp7.3 family
Family:
Phage T7-like virion assembly protein gp7.3 family
Representative Members: 7.3 (Escherichia phage T7)UniProtKB:P03751

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Small virion-associated tail protein packaged within the tail tip complex that is essential for productive adsorption and stability of the tail apparatus at the initiation of infection.

Part 3: tail fiber attachment and host lipopolysaccharide recognition
Trimeric gp17 tail fiber docking and rough LPS receptor engagementRegulatory Steptail_fiber_adsorption_step

Annotons

Tail fiber protein gp17
gp17_tail_fiber_receptor_binding
Participant: Family: Phage T7 tail fiber protein gp17 family
Family:
Phage T7 tail fiber protein gp17 family
Representative Members: 17 (Escherichia phage T7)UniProtKB:P03748

Function

structural constituent of virionGO:0039660

Processes

adhesion receptor-mediated virion attachment to host cellGO:0098671

Locations

host outer membraneGO:0044384

Six homotrimers anchor via their N-terminal domains at the gp11-gp12 junction and recognize the inner core heptose region of host Escherichia coli rough lipopolysaccharide via their C-terminal beta-helical pyramid domains, transitioning from a Reversible capsid-bound conformation to an extended vertical orientation that triggers gp12 nozzle opening and internal core ejection.