DNA gyrase activities from Rhodobacter capsulatus: analysis of target(s) of coumarins and cloning of the gyrB locus

Bacterial DNA gyrase is composed of two subunits gyrase A and B, and is responsible for negatively supercoiling DNA in an ATP-dependent manner. The coumarin antibiotics novobiocin and coumermycin are known inhibitors of bacterial DNA gyrase in vivo and in vitro. We have cloned, mapped, and partially...

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Bibliographic Details
Published in:FEMS microbiology letters 1992-05, Vol.93 (1), p.25-32
Main Authors: Kranz, Robert G., Beckman, Diana L., Foster-Hartnett, Dawn
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Aerobiosis
Amino Acid Sequence
Aminocoumarins
Anaerobiosis
Antibiotics
Cloning, Molecular
Coumarins - pharmacology
Coumermycin
Cytochrome c Group - biosynthesis
DNA gyrase
DNA Topoisomerases, Type II - genetics
DNA Topoisomerases, Type II - metabolism
Drug Resistance, Microbial
Genes, Bacterial
gyrB Gene
Molecular Sequence Data
Novobiocin
Novobiocin - pharmacology
Rhodobacter capsulatus
Rhodobacter capsulatus - drug effects
Rhodobacter capsulatus - enzymology
Rhodobacter capsulatus - genetics
Sites of action
Topoisomerase II Inhibitors
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Summary:Bacterial DNA gyrase is composed of two subunits gyrase A and B, and is responsible for negatively supercoiling DNA in an ATP-dependent manner. The coumarin antibiotics novobiocin and coumermycin are known inhibitors of bacterial DNA gyrase in vivo and in vitro. We have cloned, mapped, and partially sequenced Rhodobacter capsulatus gyrB which encodes the gyrase B subunit that is presumably involved in binding to coumarins. DNA gyrase activities from crude extracts of R. capsulatus were detected and it was shown that the R. capsulatus activity is (1) inhibited by novobiocin and coumermycin, (2) ATP-dependent and, (3) present in highly aerated and anaerobically grown cells. We previously observed that when R. capsulatus coumermycin-resistant strains are continuously recultured on media containing coumermycin they sometimes acquired mutations in hel genes (i.e., cytochromes c biogenesis mutations). We discuss the possibility that coumarins may inhibit cytochromes c biogenesis as a second target in R. capsulatus via hel (i.e., a putative ATP-dependent heme exporter).
ISSN:0378-1097
1574-6968
DOI:10.1016/0378-1097(92)90484-6