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Inhibition of vitamin B12-dependent microbial growth by nitrous oxide
1Department of Anesthesia, Massachusetts General Hospital, Boston 02114.
Life Sciences
|January 1, 1991
Summary
Nitrous oxide inhibits Escherichia coli growth by inactivating methionine synthase, an enzyme crucial for methionine synthesis. This occurs in strains lacking or having reduced activity of the cobalamin-independent pathway.
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Methionine is an essential amino acid for bacterial growth.
- Escherichia coli possesses pathways for de novo methionine synthesis.
- Cobalamin-dependent methionine synthase plays a key role in this synthesis.
Purpose of the Study:
- To investigate the effect of nitrous oxide on methionine synthesis in Escherichia coli.
- To identify the specific enzyme targeted by nitrous oxide.
Main Methods:
- Culturing auxotrophic and prototrophic Escherichia coli strains in methionine-free media.
- Administering nitrous oxide to bacterial cultures.
- Selectively depressing the cobalamin-independent pathway using sulfanilamide.
Main Results:
- Nitrous oxide inhibited the growth of an auxotrophic E. coli strain lacking the cobalamin-independent methionine synthesis pathway.
- Nitrous oxide also inhibited prototrophic E. coli when this pathway was depressed.
- Nitrous oxide was shown to inactivate cobalamin-dependent 5-methyltetrahydrofolate--homocysteine methyltransferase (methionine synthase).
Conclusions:
- Nitrous oxide effectively inactivates bacterial methionine synthase.
- This inactivation disrupts methionine synthesis, leading to growth inhibition in Escherichia coli.