The dnrO gene encodes a DNA-binding protein that regulates daunorubicin production in Streptomyces peucetius by controlling expression of the dnrN pseudo response regulator gene

Abstract

The dnrO gene is located adjacent to and divergently transcribed from the response regulator gene, dnrN, that activates the transcription of the dnrI gene, which in turn activates transcription of the daunorubicin biosynthesis genes in Streptomyces peucetius. Gene disruption and replacement of dnrO produced the dnrO ::aphII mutant strain and resulted in the complete loss of daunorubicin biosynthesis. Suppression of the dnrO ::aphII mutation by the introduction of dnrN or dnrI on a plasmid suggested that DnrO is required for the transcription of dnrN, whose product is known to be required for dnrI expression. These conclusions were supported by the effects of the dnrO mutation on expression of dnrO, dnrN and dnrI, as viewed by melC fusions to each of these regulatory genes. DnrO was overexpressed in Escherichia coli and the cell-free extract was used to conduct mobility shift DNA-binding assays. The results showed that DnrO binds specifically to the overlapping dnrN/dnrO p1 promoter region. Thus, DnrO may regulate the expression of both the dnrN and dnrO genes.

Combinatorial Regulation by a Novel Arrangement of FruA and MrpC2 Transcription Factors during Myxococcus xanthus Development

“…Therefore, the unphosphorylated receiver domain of FruA might interact directly with MrpC2 to mediate cooperative DNA binding. Receiver domains that cannot or need not be phosphorylated have been described in bacterial DNA-binding proteins (11,44,50) and in proteins that regulate circadian rhythms in bacteria (36,65) and plants (53). These proteins are sometimes called pseudo-response regulators.…”

A combination of unusual transcription factors binds cooperatively to control Myxococcus xanthus developmental gene expression

“…Although these results do not rule out the possibility that FruA is phosphorylated, our discovery of potent cooperative binding by recombinant (presumably unphosphorylated) FruA and MrpC2, which depends on the N-terminal domain of FruA, reveals an unusual function of a receiver domain that may not be phosphorylated. Receiver domains that cannot or need not be phosphorylated in order for the pseudoresponse regulator protein to function have been described in bacterial DNA-binding proteins (32)(33)(34) and in proteins that regulate circadian rhythms in bacteria (35,36) and plants (37).…”

NovG, a DNA-binding protein acting as a positive regulator of novobiocin biosynthesis

“…The inactivation of positive regulators in the biosynthetic gene clusters of various antibiotics has been reported to result in a complete loss of antibiotic production (Antó n et al, 2004;Lombó et al, 1999;Otten et al, 1995Otten et al, , 2000Pérez-Llarena et al, 1997;Wilson et al, 2001). The DnovG strains constructed in this study, however, still produced some novobiocin (see above).…”