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Iron-Dependent Transcription of the Regulatory Gene ros of Agrobacterium radiobacter

December 1997 , Volume 10 , Number  9
Pages  1,087 - 1,093

H. Hussain and A. W. B. Johnston

School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK

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Accepted 21 August 1997.

Transcription of the regulatory gene ros of Agrobacterium radiobacter requires growth in the presence of Fe although this regulation was not mediated by ros itself. The ros gene repressed its own transcription, independently of the Fe status of the growth media. It was shown that the two cysteine residues in the Ros protein were essential for the complementation of the exopolysaccharide synthesis defect of ros mutant strains. It was found that the mutation in one exo mutant strain that was complemented both by ros and by the “structural” exoY gene was not, in fact, in ros but is in some other, unknown gene. The two cysteines were also essential for the correction of this mutant. This mutant affected the expression of exoY but not of ros.

Additional keyword: autoregulation.

© 1997 The American Phytopathological Society