Studies of the Bradyrhizobium japonicum nodD sub(1) promoter: A repeated structure for the nod Box

Induction of nod genes in Rhizobium and Bradyrhizobium species is dependent on the presence of plant-produced flavonoids, the NodD protein, and the cis-acting nod box promoter sequence. Although the nodD (nodD sub(1)) gene in Rhizobium) species is constitutively expressed, nodD sub(1) expression in...

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Bibliographic Details
Published in:Journal of bacteriology 1991-01, Vol.173 (11), p.3356-3365
Main Authors: Wang, Shui Ping, Stacey, G
Format: Article
Language:English
Online Access:Get full text
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Summary:Induction of nod genes in Rhizobium and Bradyrhizobium species is dependent on the presence of plant-produced flavonoids, the NodD protein, and the cis-acting nod box promoter sequence. Although the nodD (nodD sub(1)) gene in Rhizobium) species is constitutively expressed, nodD sub(1) expression in Bradyrhizobium japonicum) is inducible by isoflavones in a manner similar to that of the nodYABC operon. A consensus nod box sequence is found 5' of the nodYABC operon, whereas a presumptive, nod box-like sequence is found 5' of the nodD sub(1) gene. As an initial step toward examining the nodD sub(1) promoter, the transcriptional start sites of the nodD sub(1) and nodYABC operons were determined and found to be 44 and 28 bp, respectively, downstream of their respective nod box sequences. A series of deletions of the nodD sub(1) promoter were constructed and fused to the lacZ gene. Analysis of the activity of these deletions clearly showed that the divergent nod box sequence was essential for nodD sub(1) induction by isoflavones or soybean seed extract.
ISSN:0021-9193