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

Robert G. Kranz, Diana L. Beckman, Dawn Foster-Hartnett

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

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).

Original languageEnglish (US)
Pages (from-to)25-32
Number of pages8
JournalFEMS Microbiology Letters
Volume93
Issue number1
DOIs
StatePublished - May 15 1992
Externally publishedYes

Keywords

  • Antibiotics
  • Coumermycin
  • DNA gyrase
  • Novobiocin
  • Rhodobacter capsulatus
  • Sites of action
  • gyrB Gene

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