OmcZ cytochrome nanowire

cellstructuremech:omcz_cytochrome_nanowire · Appendage · Appendage · Proposed

An extracellular electrically conductive Geobacter sulfurreducens filament assembled from the octaheme c-type cytochrome OmcZ; each subunit contributes a branched heme arrangement with a surface-exposed heme site to the cytochrome polymer. [DOI:10.7554/eLife.81551]

Synonyms: OmcZ nanowire; OmcZ filament

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
OmcZ octaheme c-type cytochrome	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	omcZ		ESSENTIAL	Octaheme c-type cytochrome subunit that polymerizes into the extracellular OmcZ filament and positions covalently bound hemes in a branched arrangement. `DOI:10.7554/eLife.81551` Wang et al. 2022 solved the Geobacter OmcZ filament by cryo-EM and modeled the filament as a polymer of OmcZ octaheme cytochrome subunits. `PDB:8D9M` RCSB PDB entry 8D9M is the cryo-EM model of OmcZ nanowires from Geobacter sulfurreducens and aligns polymer entity 1 to UniProtKB:Q74BG5. `PDB:7LQ5` RCSB PDB entry 7LQ5 is a 3.4 A cryo-EM model of a polymerized Geobacter sulfurreducens PCA OmcZ fragment and aligns polymer entity 1 to UniProtKB:Q74BG5 residues 25-282.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

OmcZ octaheme c-type cytochrome

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q74BG5`	Cytochrome c	omcZ	Geobacter sulfurreducens PCA (`NCBITaxon:243231`)	UNREVIEWED
Role and evidence (2 references) UniProtKB entry for the Geobacter sulfurreducens PCA omcZ gene product that is linked to the OmcZ nanowire cryo-EM structures PDB:8D9M and PDB:7LQ5. `PDB:8D9M` RCSB reports a full-length SIFTS alignment from polymer entity 1 of PDB:8D9M to UniProtKB:Q74BG5. `PDB:7LQ5` RCSB reports a SIFTS alignment from polymer entity 1 of PDB:7LQ5 to UniProtKB:Q74BG5 residues 25-282 and records NCBITaxon:243231 as the natural-source taxonomy.

Taxonomic distribution

NCBITaxon:243231 Geobacter sulfurreducens PCA — COMMON: Geobacter sulfurreducens PCA was the natural source organism for the PDB:7LQ5 cryo-EM model of polymerized OmcZ. [PDB:7LQ5]

Canonical examples

NCBITaxon:243231 Geobacter sulfurreducens PCA — Strain source of the polymerized OmcZ fragment structure solved by cryo-EM and deposited as PDB:7LQ5. [PDB:7LQ5]

Functions

branched-heme long-range electron transfer — OmcZ subunits arrange covalently bound hemes in a branched network with a surface-exposed heme site per subunit, providing a candidate structural path for long-range electron transfer in conductive OmcZ filaments.
- DOI:10.7554/eLife.81551 Wang et al. 2022 contrasted OmcZ with linear OmcS and OmcE heme chains and proposed that the OmcZ branched, surface-exposed heme arrangement may explain the filament's high conductivity.

Mechanism graphs

OmcZ subunits branch hemes for nanowire conduction (FUNCTION)

OmcZ octaheme c-type cytochromes polymerize into an extracellular filament whose branched heme arrangement and surface-exposed heme site provide a candidate structural basis for conductive OmcZ nanowires.

Subject	Predicate	Object	Evidence
OmcZ octaheme c-type cytochrome	polymerizes into	OmcZ cytochrome nanowire	`DOI:10.7554/eLife.81551` Wang et al. 2022 determined a cryo-EM structure of Geobacter sulfurreducens OmcZ filaments formed from the OmcZ octaheme cytochrome.
OmcZ octaheme c-type cytochrome	arranges	branched heme network	`DOI:10.7554/eLife.81551` Wang et al. 2022 reported that OmcZ heme packing and between-subunit coordination differ from the linear OmcS and OmcE heme chains.
branched heme network	exposes	surface-exposed heme site	`DOI:10.7554/eLife.81551` Wang et al. 2022 proposed that the surface-exposed heme in each OmcZ subunit may help explain conductive biofilm network formation.
branched heme network	supports	long-range extracellular electron transfer	`DOI:10.7554/eLife.81551` Wang et al. 2022 proposed that the branched OmcZ heme architecture could account for highly conductive cytochrome filaments.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral protein-family grounding for OmcZ cytochrome nanowire subunits. The first OmcZ cytochrome nanowire record uses an unreviewed Geobacter sulfurreducens PCA UniProtKB example but keeps the component itself label-only because no exact InterPro, Pfam or NCBIfam family CURIE for the extracellular OmcZ filament subunit class was verified.

Evidence

DOI:10.7554/eLife.81551 Wang, Chan, Suciu et al. 2022, Structure of Geobacter OmcZ filaments suggests extracellular cytochrome polymers evolved independently multiple times, eLife.
PDB:8D9M RCSB PDB entry 8D9M is a 4.2 A helical cryo-EM model of Geobacter sulfurreducens OmcZ nanowires associated with EMDB map EMD-27266.
DOI:10.1038/s41564-022-01315-5 Gu, Guberman-Pfeffer, Srikanth et al. 2023, Structure of Geobacter cytochrome OmcZ identifies mechanism of nanowire assembly and conductivity, Nature Microbiology.
PDB:7LQ5 RCSB PDB entry 7LQ5 is a 3.4 A cryo-EM model of polymerized OmcZ from Geobacter sulfurreducens PCA associated with EMDB map EMD-23481.

Curation history

2026-09-11T15:14:09Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-11T15:14:56Z codex · EXPANDED_RECORD — Added OmcZ cytochrome nanowire synonymy, a label-only OmcZ component with a Geobacter sulfurreducens PCA UniProt example, Geobacter sulfurreducens source taxon rows, electron-transfer function evidence, a narrow OmcZ function graph, and a TODO for exact OmcZ family grounding.
2026-09-11T15:24:08Z codex · ADDRESS_REVIEW — Resolved #507 by narrowing OmcZ taxon rows to Geobacter sulfurreducens PCA and adding PDB:7LQ5 exact-strain evidence, and resolved #508 by marking the branched-heme conduction path as a candidate structural model.

Source: data/structures/appendage/omcz_cytochrome_nanowire.yaml