Journal of Molecular Evolution

, Volume 29, Issue 5, pp 422–428

Glutamine synthetase II inRhizobium: Reexamination of the proposed horizontal transfer of DNA from eukaryotes to prokaryotes

Authors

  • Robert G. Shatters
    • Program in Genetics and Cell BiologyWashington State University
  • Michael L. Kahn
    • Institute of Biological ChemistryWashington State University
    • Department of MicrobiologyWashington State University
Article

DOI: 10.1007/BF02602912

Cite this article as:
Shatters, R.G. & Kahn, M.L. J Mol Evol (1989) 29: 422. doi:10.1007/BF02602912

Summary

We have determined the DNA sequence of aRhizobium meliloti gene that encodes glutamine synthetase II (GSII). The deduced amino acid sequence was compared to that ofBradyrhizobium japonicum GSII and those of various plant and mammalian glutamine synthetases (GS) in order to evaluate a proposal that the gene for this enzyme was recently transferred from plants to their symbiotic bacteria. There is 83.6% identity between theR. meliloti andB. japonicum proteins. The bacterial GSII proteins average 42.5% identity with the plant GS proteins and 41.8% identity with their mammalian counterparts. The plant proteins average 53.7% identity with the mammalian proteins. Thus, the GS proteins are highly conserved and the divergence of these proteins is proportional to the phylogenetic divergence of the organisms from which the sequences were determined. No transfer of genes across large taxonomic gaps is needed to explain the presence of GSII in these bacteria.

Key words

Glutamine synthetaseRhizobiumBradyrhizobiumProtein evolution

Copyright information

© Springer-Verlag New York Inc 1989