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Tetrameric structure and cellular location of catechol 2,3-dioxygenase
J Winkler1, L D Eltis, D F Dwyer
1Department of Microbiology, National Research Center for Biotechnology, Braunschweig, Germany.
Archives of Microbiology
|January 1, 1995
Summary
Catechol 2,3-dioxygenase, crucial for aromatic compound breakdown, was studied using electron microscopy. This enzyme, found in the cytoplasm of Pseudomonas putida and Escherichia coli, has a tetrahedral structure of four subunits.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- The TOL plasmid of Pseudomonas putida (pWWO) encodes catechol 2,3-dioxygenase, an enzyme involved in the meta-cleavage pathway of aromatic compound degradation.
- Understanding the structure and localization of this enzyme is important for comprehending microbial catabolism and potential biotechnological applications.
Purpose of the Study:
- To elucidate the quaternary structure of purified catechol 2,3-dioxygenase.
- To determine the subcellular localization of catechol 2,3-dioxygenase in both Pseudomonas putida and Escherichia coli.
Main Methods:
- Electron microscopy was employed to visualize negatively stained samples of purified catechol 2,3-dioxygenase.
- Monoclonal antibodies specific to catechol 2,3-dioxygenase were generated.
- Post-embedding immunoelectron microscopy using the protein A-gold technique was performed for in situ enzyme localization.
Main Results:
- Electron microscopy revealed that catechol 2,3-dioxygenase comprises four subunits arranged in a tetrahedral conformation.
- Immunoelectron microscopy confirmed the cytoplasmic localization of catechol 2,3-dioxygenase in both Pseudomonas putida (pWWO) and Escherichia coli (pAW31).
Conclusions:
- Catechol 2,3-dioxygenase possesses a defined quaternary structure with tetrahedral symmetry.
- The enzyme is located in the cytoplasm of both Pseudomonas putida and Escherichia coli, indicating a conserved localization for this key catabolic enzyme.