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A catalase from Streptomyces coelicolor A3(2)
G E Walker1, Bryan Dunbar2, Iain S Hunter2
1Departments of Biochemistry1 and Genetics2, University of Glasgow, Glasgow G12 8QQ, UK.
Microbiology (Reading, England)
|June 1, 1995
Summary
This study purified catalase from Streptomyces coelicolor, revealing a homotetrameric structure and high sequence similarity to other catalases. Elevated catalase activity was observed in stationary-phase cells, suggesting a role in bacterial stress response.
Area of Science:
- Microbiology
- Enzymology
- Biochemistry
Background:
- Catalase is a crucial enzyme protecting cells from oxidative damage.
- Streptomyces coelicolor is a Gram-positive bacterium with industrial and medical relevance.
- Understanding catalase function in bacteria can provide insights into oxidative stress mechanisms.
Purpose of the Study:
- To purify and characterize catalase from Streptomyces coelicolor.
- To investigate the enzyme's structural properties and sequence homology.
- To examine catalase activity during bacterial growth phases.
Main Methods:
- A three-step purification protocol involving ammonium sulfate fractionation, Phenyl-Sepharose, and Mono Q chromatography.
- Native protein characterization, including subunit molecular weight determination.
- N-terminal and internal peptide sequencing for homology analysis.
- Southern blot analysis to determine gene copy number.
- Enzyme activity assays throughout batch culture growth.
Main Results:
- Catalase was purified 250-fold with a 35% yield, achieving a specific activity of 110,000 U mg-1.
- The native enzyme is a homotetramer with a subunit molecular weight of 55,000.
- Sequence analysis revealed significant homology to other microbial and mammalian catalases.
- Southern blot confirmed a single catalase gene in S. coelicolor.
- Catalase activity was significantly elevated in stationary-phase cells.
Conclusions:
- Streptomyces coelicolor possesses a well-conserved catalase enzyme.
- The enzyme's activity increases during the stationary phase, indicating a potential role in managing oxidative stress in this growth stage.
- This research provides a foundation for further studies on catalase function and regulation in Streptomyces species.