Letter | Published:

Evidence for the B12-dependent enzyme ethanolamine deaminase in Salmonella

Naturevolume 254pages150151 (1975) | Download Citation



THE enteric bacteria Escherichia coli and Salmonella typhimurium, like man, do not synthesise significant amounts of cobalamin (B12) compounds and thus depend on exogenous vitamin B12 for their B12-dependent enzymes1. In E. coli and S. typhimurium the only reported B12-dependent enzyme catalyses the final step in methionine biosynthesis—the methylation of homocysteine to give methionine. These bacteria do not depend on exogenous B12 for growth, however, for they have an alternative B12-independent homocysteine transmethylase (non-B12 enzyme) which can catalyse the same reaction. The non-B12 transmethylase is much less efficient than the corresponding B12-dependent enzyme: in bacteria grown in the absence of vitamin B12, the non-B12-dependent enzyme comprises 3–5 % of the total soluble protein2. If this enzyme is blocked by mutation, the mutant bacteria require either methionine itself or exogenous B12, which allows them to utilise the B12-dependent enzyme for methionine biosynthesis3. We have sought other B12-dependent enzymes in S. typhimurium and found evidence for an ethanolamine deaminase. We did not find other examples of parallel non-B12-dependent and B12-dependent enzymes in S. typhimurium. E. coli also seems to have an ethanolamine deaminase.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Cauthen, S. E., Foster, M. A., and Woods, D. D., Biochem. J., 98, 630–635 (1966).

  2. 2

    Whitfield, C. D., Steers, E. J., Jr., and Weissbach, H., J. biol. Chem., 245, 390–401 (1970).

  3. 3

    Woods, D. D., Foster, M. A., and Guest, J. R., Transmethylation and Methionine Biosynthesis (edit. by Shapiro, S. K., and Schlenk, F.), 138–154 (University of Chicago, 1965).

  4. 4

    Barker, H. A., Ann. Rev. Biochem., 41, 55–90 (1972).

  5. 5

    Gutnick, D., Calvo, J. M., Klopotowski, T., and Ames, B. N., J. Bact., 100, 215–219 (1969).

  6. 6

    Jones, A., and Turner, J. M., J. gen. Microbiol., 67, 379–381 (1971).

  7. 7

    Roth, J. R., Methods in Enzymology (edit. by Tabor, H., and Tabor, C. W.), 17 a, 3–35 (Academic, New York, 1970).

  8. 8

    Bradbeer, C., J. biol. Chem., 240, 4675–4681 (1965).

  9. 9

    Hershey, A. D., and Chase, M., J. gen. Physiol., 36, 39–56 (1952).

Download references

Author information


  1. Department of Nutritional Sciences, University of California, Berkeley, California, 94820

    •  & JUDY T. CHANG


  1. Search for GEORGE W. CHANG in:

  2. Search for JUDY T. CHANG in:

About this article

Publication history



Issue Date



Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.