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Mol Microbiol. 1994 Apr;12(1):23-30.

A mutation in the receiver domain of the Agrobacterium tumefaciens transcriptional regulator VirG increases its affinity for operator DNA.

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Section of Microbiology, Cornell University, Ithaca, New York 14853.


We fused the wild-type Agrobacterium tumefaciens virG gene and the constitutive virGN54D allele to the malE gene of Escherichia coli, and studied the binding of MBP-VirG fusions to the autoregulated virG promoter. MBP-VirGN54D protein bound this promoter with 10-fold higher affinity than MBP-VirG, and bound to vir box I with eightfold higher affinity than to vir box III. Disruption of vir box III did not alter the affinity for vir box I, suggesting a lack of cooperativity between these sites. We provide evidence that protein bound at a single vir box may have a higher oligomeric state than non-bound protein, and that a DNA distortion adjacent to vir box I may occur during activation.

[Indexed for MEDLINE]

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