Open AccessDNA gyrase activities from Rhodobacter capsulatus : analysis of target(s) of coumarins and cloning of the gyrB locus
Author(s) -
Kranz Robert G.,
Beckman Diana L.,
FosterHartnett Dawn
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05035.x
Subject(s) - dna gyrase , novobiocin , rhodobacter , dna supercoil , biology , oxolinic acid , genetics , biochemistry , dna , escherichia coli , gene , mutant , nalidixic acid , dna replication , bacteria
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).