1887

Abstract

Both GcvA and Lrp are required for normal regulation of the operon. Moving the GcvA-binding sites 3 and 2 and the Lrp-binding region either closer to, or further away from, the promoter by approximately one helical turn of DNA resulted in a less than twofold decrease in glycine-mediated activation or inosine-mediated repression of a fusion. Moving these sites approximately two helical turns of DNA away from the promoter resulted in a further loss of both activation and repression; moving these sites approximately three helical turns of DNA from the promoter resulted in an essentially complete loss of both glycine-mediated activation and inosinemediated repression. However, when these sites were moved by approximately 1.5 and 2.5 helical turns of DNA away from the promoter, there was a complete loss of both glycine-mediated activation and inosine-mediated repression of the fusion. The flexibility in the absolute distance of the GcvA- and Lrp-binding sites relative to the promoter, but strict orientation dependence of these sites is consistent with a possible protein-protein interaction of either GcvA, Lrp, or both of these proteins with RNA polymerase. Because of the location of these target sites relative to the promoter, it is also likely that DNA looping is required for this mechanism of regulation.

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/content/journal/micro/10.1099/00221287-144-5-1417
1998-05-01
2019-10-18
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-144-5-1417
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