cyanophycin granule

cellstructuremech:cyanophycin_granule · Inclusion · Inclusion body · Proposed

A bacterial storage inclusion in which insoluble cyanophycin polymer accumulates as cytoplasmic granules that store fixed nitrogen and carbon for later mobilization. [DOI:10.5772/intechopen.77049]

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
cyanophycin polymer	Small molecule	part of	`CHEBI:65319`			ESSENTIAL	Insoluble poly(amide) storage material that forms the granule core and stores fixed nitrogen plus carbon. `DOI:10.5772/intechopen.77049` Watzer and Forchhammer 2018 review cyanophycin as a nitrogen- and carbon-rich reserve polymer that accumulates as intracellular granules.

Taxonomic distribution

NCBITaxon:2 Bacteria — VARIABLE: Cyanophycin occurs in many cyanobacteria and in a smaller set of heterotrophic bacteria, but is absent from most bacterial lineages. [DOI:10.5772/intechopen.77049]

Canonical examples

NCBITaxon:1148 Synechocystis sp. PCC 6803 — Unicellular cyanobacterium used for CphA-GFP localization and cyanophycin accumulation experiments. [DOI:10.1128/AEM.01298-18]

Functions

fixed nitrogen and carbon storage — Cyanophycin granules sequester nitrogen-rich cyanophycin polymer as a storage reserve that can be mobilized when cells need nitrogen or carbon.
- DOI:10.5772/intechopen.77049 Watzer and Forchhammer 2018 review cyanophycin as a nitrogen- and carbon-rich reserve polymer in bacteria.
- DOI:10.1128/AEM.01298-18 Watzer et al. 2018 assayed Synechocystis cyanophycin accumulation and mobilization during nitrogen supply shifts.

Mechanism graphs

CphA builds cyanophycin stores at the granule surface (ASSEMBLY)

Cyanophycin synthetase polymerizes cyanophycin and localizes to granule surfaces while insoluble cyanophycin polymer accumulates as a nitrogen- and carbon-rich storage granule.

Subject	Predicate	Object	Evidence
cyanophycin synthetase	polymerizes	cyanophycin polymer	`DOI:10.1128/AEM.01298-18` Watzer et al. 2018 used CphA-GFP to track CphA movement from cytoplasmic foci to cyanophycin granule surfaces during synthesis.
cyanophycin polymer	accumulates as	cyanophycin granule	`DOI:10.5772/intechopen.77049` Watzer and Forchhammer 2018 review cyanophycin as an intracellular granule-forming bacterial storage polymer.
cyanophycin granule	stores	stored fixed nitrogen and carbon	`DOI:10.5772/intechopen.77049` Watzer and Forchhammer 2018 review cyanophycin as a reserve polymer that stores nitrogen and carbon.

Discussions

CURATION_TODO (OPEN): Resolve an exact family grounding for the CphA cyanophycin synthetase assembly-graph node. GO molecular-function terms cover cyanophycin synthetase activities, but exact CphA-family InterPro, Pfam or NCBIfam groundings should be chosen by a focused homology pass rather than guessed. CphA is tracked as cyanophycin-polymerization machinery in the graph rather than as a granule component.

Evidence

DOI:10.5772/intechopen.77049 Watzer and Forchhammer 2018, Cyanophycin: A Nitrogen-Rich Reserve Polymer, in Cyanobacteria.
DOI:10.1128/AEM.01298-18 Watzer et al. 2018, Cyanophycin Synthesis Optimizes Nitrogen Utilization in the Unicellular Cyanobacterium Synechocystis sp. Strain PCC 6803, Applied and Environmental Microbiology.

Curation history

2026-09-10T09:30:09Z claude · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-10T09:30:42Z claude · EXPANDED_RECORD — Added the ChEBI-grounded cyanophycin polymer core, CphA cyanophycin synthetase granule-surface machinery, bacterial taxonomic scope, a Synechocystis sp. PCC 6803 canonical example, a fixed nitrogen and carbon storage function, record-level evidence, a CphA assembly graph and a CphA grounding TODO.
2026-09-10T09:41:07Z claude · EDITED_RECORD — Removed CphA cyanophycin synthetase from components, retained it as assembly-graph polymerization machinery without a component_ref, and retargeted the CphA grounding TODO to the assembly graph.

Source: data/structures/inclusion/cyanophycin_granule.yaml