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The virC and virD operons of the Agrobacterium Ti plasmid are regulated by the ros chromosomal gene: analysis of the cloned ros gene
The ros chromosomal gene is present in octopine and nopaline strains of Agrobacterium tumefaciens as well as in Rhizobium meliloti. This gene encodes a 15.5-kda protein that specifically represses the virC and virD operons in the virulence region of the Ti plasmid. The ros gene was cloned from a gen...
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Published in: | Journal of Bacteriology 1991-04, Vol.173 (8), p.2608-2616 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The ros chromosomal gene is present in octopine and nopaline strains of Agrobacterium tumefaciens as well as in Rhizobium meliloti. This gene encodes a 15.5-kda protein that specifically represses the virC and virD operons in the virulence region of the Ti plasmid. The ros gene was cloned from a genomic bank by electroporation and complementation in Agrobacterium cells. Reporter fusion to the ros gene indicates that the level of transcription is controlled in part by autoregulation. A consensus inverted repeat sequence present in the ros promoter and in the virC and virD promoters of pTiC58, pTiA6, and pRiA4b suggests that a specific Ros binding site exists in these promoters. In the virc and virD promoter region, this binding site is within a cluster of vir box consensus sequences in which the VirG protein binds. This suggests possible binding competition between Ros and VirG at the virC and virD promoters. That the Ros protein binds DNA is suggested by the presence of a 'zinc finger' consensus sequence in the protein |
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ISSN: | 0021-9193 1098-5530 1067-8832 |
DOI: | 10.1128/jb.173.8.2608-2616.1991 |