bacterial thylakoid

GO:0030075 · Membrane organelle · Other · Proposed

A thylakoid that is derived from and attached to, but not necessarily continuous with, the plasma membrane, and is not enclosed in a plastid. It bears the photosynthetic pigments in photosynthetic cyanobacteria. [GO:0030075]

Synonyms: plasma membrane-derived thylakoid

Has part: plasma membrane-derived thylakoid membrane (GO:0031676); plasma membrane-derived thylakoid lumen (GO:0031979); plasma membrane-derived photosystem I (GO:0030094); plasma membrane-derived thylakoid photosystem II (GO:0030096)

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
plasma membrane-derived thylakoid membrane	Lipid	part of	`GO:0031676`	ESSENTIAL	Pigmented cyanobacterial thylakoid membrane derived from the plasma membrane and embedded with the photosystems and other photosynthetic electron-transport complexes. `GO:0031676` GO:0031676 defines the plasma membrane-derived thylakoid membrane as the pigmented membrane of a bacterial thylakoid. `DOI:10.1016/j.molp.2017.09.019` Casella et al. 2017 mapped photosystem I and photosystem II organization within native Synechocystis thylakoid membranes.
plasma membrane-derived thylakoid photosystem II	Protein complex	part of	`GO:0030096`	UNKNOWN	P680 reaction-center complex in the bacterial thylakoid that oxidizes water and reduces plastoquinone during oxygenic photosynthesis. `GO:0030096` GO:0030096 defines the plasma membrane-derived thylakoid photosystem II complex. `DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 review PSII as a major cyanobacterial thylakoid electron-transport complex.
cytochrome b6f complex	Protein complex	part of	`GO:0009512`	UNKNOWN	Thylakoid membrane complex that links plastoquinol oxidation to proton translocation across the bacterial thylakoid membrane. `DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 place cytochrome b6f between PSII and PSI in the thylakoid electron-transport chain.
plasma membrane-derived photosystem I	Protein complex	part of	`GO:0030094`	UNKNOWN	Light-dependent oxidoreductase in the bacterial thylakoid that receives electrons downstream of cytochrome b6f and transfers them toward ferredoxin. `GO:0030094` GO:0030094 defines plasma membrane-derived photosystem I as a complex located in the bacterial thylakoid. `DOI:10.1016/j.molp.2017.09.019` Casella et al. 2017 mapped PSI distribution and mobility in native Synechocystis thylakoid membranes.
proton-transporting ATP synthase complex	Protein complex	part of	`GO:0045259`	UNKNOWN	Membrane enzyme that uses the trans-thylakoid proton motive force to synthesize ATP on the cytoplasmic side of the bacterial thylakoid membrane. `DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 include ATP synthase among thylakoid complexes that convert light energy into ATP and reducing power.

Taxonomic distribution

NCBITaxon:1117 Cyanobacteriota — COMMON: Bacterial thylakoids occur in most cyanobacteria, while Gloeobacter-like lineages perform oxygenic photosynthesis at the plasma membrane and lack internal thylakoids. [DOI:10.1146/annurev-cellbio-120823-022747]

Canonical examples

NCBITaxon:1148 Synechocystis sp. PCC 6803 — Cyanobacterial model used to probe de novo thylakoid membrane biogenesis and dynamics. [DOI:10.1038/s41467-021-23680-1]

Functions

photosynthetic electron transport chain GO:0009767 — Bacterial thylakoids organize PSII, cytochrome b6f and PSI so light-driven electron transport can move electrons from water toward ferredoxin while contributing to a trans-thylakoid proton gradient.
- DOI:10.1146/annurev-cellbio-120823-022747 Perez-Boerema et al. 2024 review thylakoid electron transport as the membrane process that converts light into chemical energy.
photosynthetic ATP synthesis — The plasma membrane-derived thylakoid membrane separates the bacterial thylakoid lumen from the cytoplasm so proton accumulation can drive ATP synthase.
- DOI:10.1146/annurev-cellbio-120823-022747 Perez-Boerema et al. 2024 describe proton motive force generation across thylakoid membranes and ATP synthase use of that gradient.

Mechanism graphs

Bacterial thylakoids localize photosynthetic complexes (FUNCTION)

The plasma membrane-derived thylakoid membrane bounds the cyanobacterial thylakoid lumen and houses the photosynthetic complexes that build a proton motive force for ATP synthesis.

Subject	Predicate	Object	Evidence
plasma membrane-derived thylakoid membrane	bounds	bacterial thylakoid	`GO:0031676` GO:0031676 defines the membrane as part of a plasma membrane-derived thylakoid.
plasma membrane-derived thylakoid membrane	encloses	plasma membrane-derived thylakoid lumen	`GO:0031979` GO:0031979 defines the lumen as the volume enclosed by a plasma membrane-derived thylakoid.
plasma membrane-derived thylakoid membrane	houses	plasma membrane-derived thylakoid photosystem II	`DOI:10.1016/j.molp.2017.09.019` Casella et al. 2017 mapped PSII within native Synechocystis thylakoid membranes.
plasma membrane-derived thylakoid membrane	houses	plasma membrane-derived photosystem I	`DOI:10.1016/j.molp.2017.09.019` Casella et al. 2017 mapped PSI distribution and mobility in native Synechocystis thylakoid membranes.
plasma membrane-derived thylakoid photosystem II	reduces	plastoquinone pool	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 review PSII and plastoquinone as upstream thylakoid electron carriers.
plastoquinone pool	feeds electrons to	cytochrome b6f complex	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 describe electron transfer from plastoquinone to cytochrome b6f in the thylakoid chain.
cytochrome b6f complex	contributes to	trans-thylakoid proton motive force	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 review generation of proton motive force by thylakoid electron transport.
cytochrome b6f complex	feeds electrons to	plasma membrane-derived photosystem I	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 place cytochrome b6f upstream of PSI in thylakoid electron transport.
trans-thylakoid proton motive force	powers	proton-transporting ATP synthase complex	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 connect the thylakoid proton gradient to ATP synthase activity.
proton-transporting ATP synthase complex	carries out	photosynthetic ATP synthesis	`DOI:10.1146/annurev-cellbio-120823-022747` Perez-Boerema et al. 2024 describe ATP synthase use of the thylakoid proton gradient.

Discussions

INTERPRETATION (RESOLVED): Keep bacterial thylakoids separate from the generic thylakoid membrane record. GO:0030075 denotes the whole plasma membrane-derived bacterial thylakoid, with GO:0031676 and GO:0031979 as membrane and lumen parts. The existing GO:0042651 record denotes only the generic pigmented membrane of cyanobacterial and plastid thylakoids.
INTERPRETATION (RESOLVED): Represent bacterial thylakoid as a membrane-bounded cellular structure without calling it an organelle. GO:0009579 describes thylakoids as membranous cellular structures and explicitly comments that they are not considered organelles. StructureKindEnum does not currently include a non-organelle membrane-bounded-compartment value, so OTHER is narrower than asserting MEMBRANE_BOUNDED_ORGANELLE.

Evidence

GO:0030075 Gene Ontology cellular-component term for bacterial thylakoid.
GO:0009579 Gene Ontology cellular-component term for thylakoid.
GO:0031676 Gene Ontology cellular-component term for the plasma membrane-derived thylakoid membrane.
GO:0031979 Gene Ontology cellular-component term for the plasma membrane-derived thylakoid lumen.
GO:0030094 Gene Ontology cellular-component term for plasma membrane-derived photosystem I.
GO:0030096 Gene Ontology cellular-component term for plasma membrane-derived thylakoid photosystem II.
DOI:10.1146/annurev-cellbio-120823-022747 Perez-Boerema et al. 2024, Evolution of Thylakoid Structural Diversity, Annual Review of Cell and Developmental Biology.
DOI:10.1016/j.molp.2017.09.019 Casella et al. 2017, Dissecting the Native Architecture and Dynamics of Cyanobacterial Photosynthetic Machinery, Molecular Plant.
DOI:10.1038/s41467-021-23680-1 Huokko et al. 2021, Probing the biogenesis pathway and dynamics of thylakoid membranes, Nature Communications.

Curation history

2026-09-12T03:41:04Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-12T03:42:31Z codex · EXPANDED_RECORD — Added the GO synonym, bacterial thylakoid part terms, GO-grounded photosynthetic membrane components, Cyanobacteriota distribution, a Synechocystis canonical example, functions, literature evidence, a nonmechanistic topology graph, and a resolved thylakoid-membrane boundary decision.
2026-09-12T03:43:00Z codex · NARROWED_EXAMPLE_EVIDENCE — Narrowed the Synechocystis canonical-example note to the thylakoid biogenesis claim directly supported by Huokko et al. 2021.
2026-09-12T03:49:52Z codex · REVIEW_FIXES — Resolved #574 by adding a plastoquinone graph node between PSII and cytochrome b6f; resolved #575 by changing structure_kind to OTHER and documenting the non-organelle thylakoid boundary.
2026-09-20T21:55:39Z codex · ADDRESSED_REVIEW — Retyped the PSII, cytochrome b6f, PSI, and ATP synthase graph nodes from GENE_OR_PROTEIN to STRUCTURE.

Source: data/structures/membrane_organelle/bacterial_thylakoid.yaml