Coumarin and quinolone action in archaebacteria: evidence for the presence of a DNA gyrase-like enzyme

Abstract

The action of novobiocin and coumermycin (two coumarins which interact with the gyrB subunit of eubacterial DNA gyrase) and ciprofloxacin (a fluoroquinolone which interacts with the gyrA subunit of DNA gyrase) was tested on several archaebacteria, including five methanogens, two halobacteria, and a thermoacidophile. Most strains were sensitive to doses of coumarins (0.02 to 10 Rg/ml) which specifically inhibit DNA gyrase in eubacteria. Ciprofloxacin inhibited growth of the haloalkaliphilic strain Natronobacterium gregoryi and of the methanogen Methanosarcina barkeri. In addition, ciprofloxacin partly relieved the sensitivity to coumarins (and vice versa). Novobiocin inhibited DNA replication in Halobacterium halobium rapidly and specifically. Topological analysis has shown that the 1.7-kilobase plasmid from Halobacterium sp. strain GRB is negatively supercoiled; this plasmid was relaxed after novobiocin treatment. These results support the existence in archaebacteria of a coumarin and quinolone target related to eubacterial DNA gyrase.The procaryotes are now divided into eubacteria and archaebacteria which constitute two independent lines of evolutionary descent (25,35,36 (13,24). In contrast, eubacteria contain a type II DNA topoisomerase (DNA gyrase) which introduces negative superturns in topologically closed DNA and a type I DNA topoisomerase (protein w) which removes negative supertums (10). Both type I and type II DNA topoisomerases also coexist in eucaryotic cells. These two enzymes only remove superturns; i.e., they have no gyrase or reverse gyrase activity (for reviews on DNA topoisomerases see references 15, 22, and 32).Eucaryotic and eubacterial type II DNA topoisomerases also differ in their antibiotic sensitivities. DNA gyrase is composed of two types of subunits, gyrA and gyrB, which are, respectively, the targets of antibiotics of the quinolone and coumarin families. Coumarins are specific inhibitors of DNA gyrase at low concentrations (<10 ,ug/ml), whereas quinolones have no activity on the eucaryotic enzyme, even at high doses. Preliminary results have been reported on the action of these antibiotics on archaebacteria. The coumarin novobiocin inhibits growth of Thermoplasma acidophilum (9) and halobacteria (4, 14). However, this does not necessarily mean that a coumarin-sensitive DNA gyrase-like enzyme exists in archaebacteria. Indeed, novobiocin has the general property of interacting with arginine-rich proteins at concentrations above 100 ,ug/ml (8) and consequently non-* Corresponding author. specifically inhibits various enzymatic activities (including eucaryotic type II DNA topoisomerase and S. acidocaldarius reverse gyrase). Thus, it was troublesome that novobiocin concentrations reported to inhibit archaebacteria varied from 0.02 to 200 ,ug/ml, depending on the strains used and the authors reporting (3,14). In addition, the archaebacterium Halobacterium halobium is resistant to the quinolones nalidixic and oxolinic acids and to the fluoroquinolones pefloxacin and norfloxacin (14). These t...

Evidence that a plasmid from a hyperthermophilic archaebacterium is relaxed at physiological temperatures

“…1). Interestingly, we have previously found that plasmids from halophilic archaebacteria-which are mesophiles-are also negatively supercoiled (15,34,35). More recent data go as far as to suggest that these halophilic plasmids are even more negatively supercoiled than eubacterial ones (6).…”

Transcriptional responses of Bacillus subtillis and thuringiensis to antibiotics and anti-tumour drugs

“…A direct comparison between the mode of action of quinolones and epipodophyllotoxins has been hampered by the lack of a living organism sensitive to both drugs. We have previously shown that archeabacteria are sensitive to inhibitors of eukaryotic and eubacterial type II DNA topoisomerase (7,8), a finding that correlates well with the intermediate phylogenetic position of archeabacteria between eukaryotes and 'classical bacteria' or eubacteria (2,9). In this respect, we have demonstrated that ciprofloxacin, novobiocin, and etoposide have a common target in Halobacterium GRB: an archaebacterial type II DNA topoisomerase (10,11).…”

“…Cleavage of pGRB-1 plasmid DNA induced by either ciprofloxacin or the antitumoral drug etoposide VP16, produced DNA fragments of identical lengths, indicating that both drugs trap the reaction intermediates between the archaebacterial DNA topoisomerase and pGRB-1 DNA at the same sites (10). It should be noted that among the archaebacteria, the halobacteria are the most sensitive organisms to DNA topoisomerase II inhibitors (7).…”

The complete genome of the crenarchaeon Sulfolobus solfataricus P2

“…The genome contains only one type II topoisomerase of the TopoVI family (Sso0968 and Sso0969) (48). No gyrase genes were detected, although Sulfolobus is novobiocin sensitive (49). Neither reverse gyrase nor TopoVI activity is inhibited by this drug (50,51).…”