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Distinct Assembly Complexes Facilitate cbb3-type Cytochrome Oxidase Maturation
Kaiwei Shen1, Yavuz Öztürk2, Jorge Jimenez-Niebla3
1Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg 79104 Freiburg, Germany; Faculty of Biology, Albert-Ludwigs-University Freiburg 79104 Freiburg, Germany.
Journal of Molecular Biology
|July 14, 2026
Summary
Bacterial cytochrome oxidase (Cox) assembly involves large, stable protein complexes, challenging previous assumptions. These complexes coordinate cofactor insertion for cbb3-Cox maturation in R. capsulatus.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Cytochrome oxidase (Cox) assembly requires precise coordination of subunit association and cofactor insertion.
- Mitochondrial Cox assembly utilizes large machineries, while bacterial assembly was thought to involve transient interactions.
Purpose of the Study:
- To investigate the mechanisms of cbb3-type Cytochrome oxidase assembly in the α-proteobacterium R. capsulatus.
- To identify the protein complexes involved in bacterial Cox maturation.
Main Methods:
- Identification and characterization of stable protein complexes during cbb3-Cox assembly.
- Analysis of cofactor insertion pathways mediated by these complexes.
Main Results:
- Three stable assembly complexes (500, 390, and 150 kDa) were identified.
- These complexes facilitate stepwise heme and copper insertion.
- A copper insertion module involving CcoG, CcoI, SenC, and CcoS was characterized.
Conclusions:
- Large multi-protein assembly machineries, similar to those in mitochondria, are essential for bacterial cbb3-Cox maturation.
- Bacterial Cox assembly is more complex than previously assumed, involving stable intermediate complexes.
- Copper loading onto CcoG and CcoI regulates the formation and stability of these assembly complexes.
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