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Sequence variation in dichloromethane dehalogenases/glutathione S-transferases
Stéphane Vuilleumier1, Nikola Ivoš1, Mariangela Dean2
1Institut für Mikrobiologie, ETH Zürich, Schmelzbergstraße 7, CH-8092 Zürich, Switzerland1.
Microbiology (Reading, England)
|March 10, 2001
Summary
Methylotrophic bacteria utilize dichloromethane (DCM) for growth using the DCM dehalogenase enzyme. Researchers identified variations in the dcmA gene across different bacterial strains, revealing minor functional differences in the resulting enzymes.
Area of Science:
- Microbial biochemistry and genetics
- Environmental microbiology
- Bioremediation
Background:
- Methylotrophic bacteria can metabolize dichloromethane (DCM), a synthetic compound, using the enzyme dichloromethane dehalogenase/glutathione S-transferase.
- Previous studies have sequenced the DCM dehalogenase (dcmA) gene from specific bacterial strains like Methylobacterium dichloromethanicum DM4 and Methylophilus sp. DM11.
Purpose of the Study:
- To investigate the genetic diversity of the dcmA gene in various DCM-degrading bacterial strains and environmental samples.
- To analyze the sequence variations and their impact on the functional properties of DCM dehalogenase enzymes.
Main Methods:
- Polymerase chain reaction (PCR) amplification and cloning of the dcmA gene from 14 different DCM-degrading strains, enrichment cultures, and wastewater sludge.
- DNA sequencing to obtain multiple dcmA gene sequences and deduce corresponding protein sequences.
- Biochemical characterization of representative DCM dehalogenase variants, including kinetic parameter determination (kcat, Km), pH optimum, and stability analysis.
Main Results:
- Eight distinct dcmA gene sequences, encoding seven different protein variants, were identified from diverse sources.
- Sequence analysis revealed limited variation, primarily base substitutions, with 16 of 19 substitutions in the dcmA gene leading to amino acid changes compared to the DM4 strain.
- Investigated DCM dehalogenase variants exhibited minor differences in kinetic parameters, pH optima, and stability, suggesting conserved functionality despite sequence variations.
Conclusions:
- The dcmA gene is genetically diverse across various DCM-degrading bacteria and environmental samples.
- Despite sequence variations, the functional properties of DCM dehalogenases remain largely conserved, indicating robustness of the metabolic pathway.
- Findings contribute to understanding microbial adaptation to xenobiotic compounds and potential applications in bioremediation.