Abstract
We have been studying the signal transduction mechanism mediated by the Rhizobium meliloti FixL and FixJ proteins in response to oxygen. FixL is a hemoprotein kinase that can sense oxygen tension and can respond to this signal by modifying its kinase activity. In vitro studies with a soluble truncated version of FixL (FixL*) demonstrated that low oxygen tension specifically augments the autophosphorylating and not the transfer activity to FixJ. FixL* also contains a phosphatase activity that is repressed under anaerobic conditions. Regulation of the phosphatase activity by oxygen is dependent on the phosphorylation state of the FixL* protein. These results demonstrate that oxygen regulates two opposing activities in the FixL protein, kinase and phosphatase, in a reciprocal manner and suggest a specific mechanism by which the oxygen tension within the nodule regulates transcription of the nitrogen fixation genes.
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© 1993 Springer Science+Business Media Dordrecht
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Lois, A.F., Weinstein, M., Monson, E.K., Ditta, G., Helinski, D.R. (1993). Oxygen Sensing and Protein Phosphorylation by the Two-Component Regulatory FixLJ System from Rhizobium Meliloti . In: Nester, E.W., Verma, D.P.S. (eds) Advances in Molecular Genetics of Plant-Microbe Interactions, Vol. 2. Current Plant Science and Biotechnology in Agriculture, vol 14. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-0651-3_21
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DOI: https://doi.org/10.1007/978-94-017-0651-3_21
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