# Microbe Profile: Paracoccus denitrificans - a versatile model

## TL;DR

Paracoccus denitrificans is a versatile bacterial model used to study electron transfer, respiration, and metabolism, with relevance to eukaryotic mitochondria.

## Contribution

The paper highlights P. denitrificans as a valuable model organism for understanding oxidative phosphorylation and diverse metabolic processes.

## Key findings

- P. denitrificans shares similarities with eukaryotic mitochondria in respiratory chain and membrane composition.
- The bacterium is used as a model for denitrification, cytochrome c biogenesis, and carbon metabolism studies.
- Modern genome-based approaches continue to advance microbiological research using P. denitrificans.

## Abstract

Electron transfer pathways of Paracoccus denitrificans. Enzymes and electron carriers are coloured according to location: orange (membrane bound) and blue (periplasmic). Electron transfer reactions are coloured black, blue and orange to indicate that they occur predominantly in the presence or absence of oxygen, or both, respectively. Note that pseudoazurin is expressed under anaerobic growth conditions and donates electrons to the nitrite, NO and N2O reductases. Abbreviations: ETF, electron transfer flavoprotein; NAR, membrane-bound nitrate reductase; NAP, periplasmic nitrate reductase; MDH, methanol dehydrogenase; MaDH, methylamine dehydrogenase; AMI, amicyanin; SOX, sulphur oxidation system; ASD, aldose sugar dehydrogenase; UQ, ubiquinone; UQH2, ubiquinol.

Paracoccus denitrificans is a metabolically versatile alphaproteobacterium first isolated in 1910 by Martinus Beijerinck. Similarities between the aerobic respiratory chain and membrane composition of P. denitrificans and those of eukaryotic mitochondria have stimulated the use of P. denitrificans as a model for oxidative phosphorylation. The organism has also been used extensively as a model for studies of denitrification, cytochrome c biogenesis, lithotrophy using thiosulphate as a source of energy, methylotrophy, and carbon metabolism more broadly. Through the application of structural biology and modern genome-based approaches, work on P. denitrificans continues to make significant contributions across multiple areas of microbiology.