The Streptomyces peucetius drrC gene encodes a UvrA-like protein involved in daunorubicin resistance and production

Abstract

The drrC gene, cloned from the daunorubicin (DNR)-and doxorubicin-producing strain of Streptomyces peucetius ATCC 29050, encodes a 764-amino-acid protein with a strong sequence similarity to the Escherichia coli and Micrococcus luteus UvrA proteins involved in excision repair of DNA. Expression of drrC was correlated with the timing of DNR production in the growth medium tested and was not dependent on the presence of DNR. Since introduction of drrC into Streptomyces lividans imparted a DNR resistance phenotype, this gene is believed to be a DNR resistance gene. The drrC gene could be disrupted in the non-DNR-producing S. peucetius dnrJ mutant but not in the wild-type strain, and the resulting dnrJ drrC double mutant was significantly more sensitive to DNR in efficiency-of-plating experiments. Expression of drrC in an E. coli uvrA strain conferred significant DNR resistance to this highly DNR-sensitive mutant. However, the DrrC protein did not complement the uvrA mutation to protect the mutant from the lethal effects of UV or mitomycin even though it enhanced the UV resistance of a uvrA ؉ strain. We speculate that the DrrC protein mediates a novel type of DNR resistance, possibly different from the mechanism of DNR resistance governed by the S. peucetius drrAB genes, which are believed to encode a DNR antiporter.Microorganisms require one or more self-resistance determinants to produce antibiotics, except in cases in which they are insensitive to the antibiotic's effect(s). The resistance genes usually are clustered with the structural (biosynthetic) and regulatory genes and encode proteins that either inactivate the antibiotic, facilitate its export, or modify the host to render it insensitive to the antibiotic (9). Multiple rather than single resistance mechanisms are often found; in this case, it is not known whether any one resistance mode is sufficient to ensure survival or antibiotic production. We address this question here.Streptomyces peucetius, which produces the important antitumor drugs daunorubicin (DNR) (4, 10) and doxorubicin (DXR) (2), contains the drrAB (17) and ric2 (8) resistance genes, which are assumed to provide self-resistance to these two antibiotics because they confer DNR and DXR resistance when introduced into Streptomyces lividans. The DrrA protein strongly resembles bacterial proteins that transport compounds by an ATP-dependent process (20), as well as the Mdr1 P glycoprotein responsible for DNR-DXR resistance of human cancer cells and known to act as an ATP-dependent transporter (19). DrrA thus is a candidate for a DNR-DXR binding and transport protein, whereas the hydrophobic DrrB protein could be responsible for binding DrrA to the bacterial membrane. The ric2 locus, which unlike drrAB is not part of the cluster of DXR production genes (8), may also be important for self-resistance. A third gene, drrC, in the same cluster of genes as is drrAB, encodes the DrrC protein described here. S. lividans drrC ϩ transformants display a DNR resistance phenotype similar to that of drrAB tran...

Structure, Function, and Evolution of Bacterial ATP-Binding Cassette Systems

“…Bacterial genomes carry several paralogues of the UvrA protein. DrrC has been shown to participate in the resistance of Streptomyces peucetius to daunorubicin and doxorubicin (287). The drrC gene encodes a DNAbinding protein whose expression is induced by daunorubicin.…”

Enhanced antibiotic production by manipulation of the Streptomyces peucetius dnrH and dnmT genes involved in doxorubicin (adriamycin) biosynthesis

“…Studies of DNR and DXR production ( Fig. 1) in this organism have elucidated the organization and regulation of many of the biosynthetic genes (11,12,21,23,29,31), as well as the mechanism of antibiotic resistance (14,19) and the regulation of DNR and DXR biosynthesis (20,28,34).…”

The Actinomycin Biosynthetic Gene Cluster ofStreptomyces chrysomallus: a Genetic Hall of Mirrors for Synthesis of a Molecule with Mirror Symmetry

“…DrrC binds to DNA in an ATP-and daunorubicin-dependent manner (19). It has DNA-binding characteristics similar to those of UvrA from E. coli and in fact can, when introduced into E. coli or Streptomyces lividans, confer resistance to daunorubicin (46). However, it cannot protect E. coli against UV radiation like UvrA does.…”