organellar chromatophore

GO:0070111 · Membrane organelle · Membrane bounded organelle · Proposed

A bacteroid-containing symbiosome in which the bacterial component is a genetically highly reduced cyanobacterium that is photosynthetically active [GO:0070111]

Has part: organellar chromatophore inner membrane (GO:0070113); organellar chromatophore outer membrane (GO:0070114); organellar chromatophore intermembrane space (GO:0070115); organellar chromatophore thylakoid (GO:0070116); organellar chromatophore thylakoid lumen (GO:0070117); organellar chromatophore thylakoid membrane (GO:0070118)

Xrefs: uniprot.location:SL-0351 — Organellar chromatophore

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
organellar chromatophore outer membrane	Lipid	part of	`GO:0070114`	UNKNOWN	Cytoplasm-facing membrane of the Paulinella organellar chromatophore envelope. `GO:0070114` GO:0070114 defines the organellar chromatophore outer membrane as the membrane facing the host cytoplasm.
organellar chromatophore inner membrane	Lipid	part of	`GO:0070113`	UNKNOWN	Stroma-facing membrane that separates the chromatophore stroma from the intermembrane space. `GO:0070113` GO:0070113 defines the inner membrane of the organellar chromatophore.
organellar chromatophore thylakoid membrane	Lipid	part of	`GO:0070118`	UNKNOWN	Internal photosynthetic membrane system that houses the complexes carrying out the light reactions of photosynthesis. `GO:0070118` GO:0070118 defines the organellar chromatophore thylakoid membrane as the internal photosynthetic membrane system.
residual peptidoglycan wall	Peptidoglycan	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Peptidoglycan layer retained between the inner and outer membranes of the cyanobacterium-derived chromatophore. `uniprot.location:SL-0351` — Organellar chromatophore UniProt Subcellular Location SL-0351 describes organellar chromatophores as retaining a residual peptidoglycan wall between the two surrounding membranes.

Taxonomic distribution

NCBITaxon:39717 Paulinella chromatophora — COMMON: Paulinella chromatophora is a photosynthetic thecate amoeba whose cyanobacterium-derived photosynthetic organelles are called chromatophores. [DOI:10.5586/asbp.2014.049]

Canonical examples

NCBITaxon:39717 Paulinella chromatophora — Model photosynthetic amoeba used to study an early-stage cyanobacterium-derived chromatophore and chromatophore protein import. [DOI:10.1073/pnas.1118800109]

Functions

photosynthesis GO:0015979 — The organellar chromatophore carries internal thylakoid membranes and photosynthetic machinery that support light-driven carbon fixation.
- GO:0070111 GO:0070111 defines the bacterial component of the organellar chromatophore as photosynthetically active.
- uniprot.location:SL-0351 — Organellar chromatophore UniProt SL-0351 describes the organellar chromatophore as housing machinery for photosynthesis and CO2 fixation.
chromatophore protein import — Nuclear-encoded Paulinella proteins are trafficked back into the chromatophore, compensating for genes lost from the reduced cyanobacterium-derived genome.
- DOI:10.1073/pnas.1118800109 Nowack and Grossman 2012 demonstrated trafficking of nucleus-encoded proteins into Paulinella chromatophora chromatophores.
- DOI:10.1016/j.cub.2017.08.010 Singer et al. 2017 characterized large-scale protein import into the early-stage Paulinella photosynthetic organelle.

Mechanism graphs

Organellar chromatophore topology and import (FUNCTION)

The Paulinella organellar chromatophore is bounded by inner and outer membranes with residual peptidoglycan between them, contains photosynthetic thylakoid membranes, and imports nuclear-encoded proteins.

Subject	Predicate	Object	Evidence
organellar chromatophore outer membrane	bounds	organellar chromatophore	`GO:0070114` GO:0070114 defines this outer membrane by its cytoplasm-facing position.
organellar chromatophore inner membrane	bounds	organellar chromatophore	`GO:0070113` GO:0070113 defines the inner organellar chromatophore membrane by its position between stroma and intermembrane space.
residual peptidoglycan wall	is retained between envelope membranes of	organellar chromatophore	`uniprot.location:SL-0351` — Organellar chromatophore UniProt SL-0351 places a residual peptidoglycan wall between the two surrounding chromatophore membranes.
organellar chromatophore thylakoid membrane	supports	photosynthesis	`GO:0070118` GO:0070118 defines the organellar chromatophore thylakoid membrane as the internal membrane system carrying light-reaction complexes.
chromatophore protein import	imports proteins into	organellar chromatophore	`DOI:10.1073/pnas.1118800109` Nowack and Grossman 2012 demonstrated protein trafficking into chromatophores.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for the residual organellar chromatophore peptidoglycan wall and the Paulinella chromatophore protein-import machinery. The first organellar chromatophore record grounds exact GO membrane terms and records protein import as a demonstrated function, but no exact CURIE was asserted for the retained peptidoglycan wall or the still-resolving import machinery.

Evidence

GO:0070111 Gene Ontology cellular-component term for organellar chromatophore.
GO:0009536 Gene Ontology cellular-component term for plastid.
GO:0070113 Gene Ontology cellular-component term for organellar chromatophore inner membrane.
GO:0070114 Gene Ontology cellular-component term for organellar chromatophore outer membrane.
GO:0070116 Gene Ontology cellular-component term for organellar chromatophore thylakoid.
GO:0070115 Gene Ontology cellular-component term for organellar chromatophore intermembrane space.
GO:0070118 Gene Ontology cellular-component term for organellar chromatophore thylakoid membrane.
GO:0070117 Gene Ontology cellular-component term for organellar chromatophore thylakoid lumen.
uniprot.location:SL-0351 — Organellar chromatophore UniProt Subcellular Location entry SL-0351 maps to GO:0070111 and describes the Paulinella photosynthetic organelle as an organellar chromatophore.
DOI:10.5586/asbp.2014.049 Nowack 2014 reviews the transition of the Paulinella cyanobacterium-derived endosymbiont into an organelle.
DOI:10.1073/pnas.1118800109 Nowack and Grossman 2012 studied protein trafficking into Paulinella chromatophora chromatophores.
DOI:10.1016/j.cub.2017.08.010 Singer et al. 2017 studied massive protein import into the early-stage Paulinella photosynthetic organelle.
DOI:10.1111/jpy.13003 Gabr, Grossman and Bhattacharya 2020 review Paulinella as a model for plastid primary endosymbiosis.

Curation history

2026-09-12T12:08:07Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-12T12:09:17Z codex · EXPANDED_RECORD — Added plastid parentage, organellar chromatophore membrane and thylakoid part terms, GO-grounded membrane components, the residual peptidoglycan wall, Paulinella chromatophora distribution and example, photosynthesis and protein-import functions, a nonmechanistic topology graph, and a grounding TODO for the peptidoglycan wall and import machinery.
2026-09-12T12:09:37Z codex · FIXED_GRAPH_EDGE — Retargeted the residual peptidoglycan wall graph edge to the whole organellar chromatophore and added record-level GO evidence rows for the chromatophore intermembrane space and thylakoid lumen.
2026-09-12T12:16:51Z codex · ADDRESS_REVIEW — Resolved #643 by adding GO:0009536 plastid as record-level evidence for the parent assertion; resolved #644 by removing the generic GO:0070112 organellar chromatophore membrane localization term from has_part and record-level evidence.

Source: data/structures/membrane_organelle/organellar_chromatophore.yaml