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Formate hydrogenlyase system in Salmonella typhimurium LT2
European Journal of Biochemistry
|January 3, 1977
Summary
Researchers isolated Salmonella typhimurium mutants to study the formate hydrogenylase system. This revealed distinct mutant classes and a missing factor essential for formate dehydrogenase 2 activity, leading to a revised system model.
Area of Science:
- Microbiology
- Enzymology
- Molecular Biology
Background:
- The multienzymic formate hydrogenylase system in Salmonella typhimurium is crucial for anaerobic respiration.
- Understanding the components and interactions within this system is key to elucidating metabolic pathways.
Purpose of the Study:
- To investigate the factors involved in the Salmonella typhimurium formate hydrogenylase system.
- To characterize different mutant classes affecting specific enzyme activities.
Main Methods:
- Isolation and characterization of Salmonella typhimurium mutants unable to reduce benzyl viologen anaerobically.
- Enzyme activity assays (formate dehydrogenase, hydrogenase) on mutant extracts.
- Complementation studies using mixtures of mutant extracts.
Main Results:
- Identified four classes of mutants (FHL-A, FHL-B, FHL-C, FHL-D) with distinct deficiencies in formate dehydrogenase 1, formate dehydrogenase 2, and/or hydrogenase activities.
- Mutations in fdhA, fdhB, hyd, and fhlD genes were mapped to specific chromosomal locations.
- Restoration of enzyme activities in mixed mutant extracts suggested a heat- and oxygen-sensitive factor, likely missing in FHL-D mutants but present in FHL-C mutants.
Conclusions:
- A new model for the formate hydrogenylase system is proposed.
- Hydrogenase activity appears to directly transfer electrons to benzyl viologen within this system.