A haemoprotein with kinase activity encoded by the oxygen sensor of Rhizobium meliloti

Article metrics

Abstract

THE expression of the nitrogen-fixation genes of Rhizobium meliloti is controlled by oxygen1,2. These genes are induced when the free oxygen concentration is reduced to microaerobic levels. Two regulator proteins, FixL and FixJ, initiate the oxygen-response cascade, and the genes that encode them have been cloned2,3. The fixL product seems to be a transmembrane sensor that modulates the activity of the fixJ product, a cytoplasmic regulator3. FixL and FixJ are homologous to a family of bacterial two-component regulators4, for which the mode of signal transduc-tion is phosphorylation (reviewed in refs 5–9). We report here the purification of both FixJ and a soluble truncated FixL (FixL*), overproduced from a single plasmid construct. FixL* catalyses its own phosphorylation and the transfer of the γ-phosphate of ATP to Fix J. The resulting FixJ–phosphate linkage is sensitive to base, as are the aspartyl phosphates of homologous systems. Visible spectra of purified FixL* show that it is an oxygen-binding haemoprotein. We propose that FixL senses oxygen through its haem moiety and transduces this signal by controlling the phos-phorylation of FixJ.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1

    Ditta, G., Virts, E., Palomares, A. & Kim, C.-H. J. Bact. 169, 3217–3223 (1987).

  2. 2

    Virts, E. L., Stanfield, S. W., Helinski, D. R. & Ditta, G. S. Proc natn. Acad. Sci. USA 85, 3062–3065 (1988).

  3. 3

    David, M. et al. Cell 54, 671–683 (1988).

  4. 4

    Nixon, B. T., Ronson, C. W. & Ausubel, F. M. Proc. natn. Acad. Sci. USA 83, 7850–7854 (1986).

  5. 5

    Stock, A. M. et al. Cold Spring Harb. Symp. quant. Biol. 53, 49–57 (1989).

  6. 6

    Stock, J. B., Ninfa, A. J. & Stock, A. M. Microbiol. Rev. 53, 450–490 (1989).

  7. 7

    Stock, J. B., Stock, A. M. & Mottonen, J. M. Nature 344, 395–400 (1990).

  8. 8

    Albright, L. M., Huala, E. & Ausubel, F. M. A. Rev. Genet. 23, 311–336 (1989).

  9. 9

    Gross, R., Arico, B. & Rappouli, R. Molec. Microbiol. 3, 1661–1667 (1989).

  10. 10

    Weiss, V. & Magasanik, B. Proc. natn. Acad. Sci. USA 85, 8919–8923 (1988).

  11. 11

    Forst, S., Delgado, J. & Inouye, M. Proc. natn. Acad. Sci. USA 86, 6052–6056 (1989).

  12. 12

    Bourret, R. B., Hess, J. F. & Simon, M. L. Proc. natn. Acad. Sci. USA 87, 41–45 (1990).

  13. 13

    Melchers, L. S. et al. EMBO J. 8, 1919–1925 (1989).

  14. 14

    Gibson, T. J. thesis, Cambridge Univ., UK (1984).

  15. 15

    Hess, J. F., Bourret, R. B. & Simon, M. I. Nature 336, 139–143 (1988).

  16. 16

    Jin, S. et al. J. Bact. 172, 525–530 (1990).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gilles-Gonzalez, M., Ditta, G. & Helinski, D. A haemoprotein with kinase activity encoded by the oxygen sensor of Rhizobium meliloti. Nature 350, 170–172 (1991) doi:10.1038/350170a0

Download citation

Further reading

Comments

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.