Both DNA gyrase and reverse gyrase are present in the hyperthermophilic bacterium Thermotoga maritima.

Like all hyperthermophiles yet tested, the bacterium Thermotoga maritima contains a reverse gyrase. Here we show that it contains also a DNA gyrase. The genes top2A and top2B encoding the two subunits of a DNA gyrase-like enzyme have been cloned and sequenced. The Top2A (type II DNA topoisomerase A protein) is more similar to GyrA (DNA gyrase A protein) than to ParC [topoisomerase IV (Topo IV) C protein]. The difference is especially striking at the C-terminal domain, which differentiates DNA gyrases from Topo IV. DNA gyrase activity was detected in T. maritima and purified to homogeneity using a novobiocin-Sepharose column. This hyperhermophilic DNA gyrase has an optimal activity around 82-86 degrees C. In contrast to plasmids from hyperthermophilic archaea, which are from relaxed to positively supercoiled, we found that the plasmid pRQ7 from Thermotoga sp. RQ7 is negatively supercoiled. pRQ7 became positively supercoiled after addition of novobiocin to cell cultures, indicating that its negative supercoiling is due to the DNA gyrase of the host strain. The findings concerning DNA gyrase and negative supercoiling in Thermotogales put into question the role of reverse gyrase in hyperthermophiles.

[1]  M. Duguet,et al.  When helicase and topoisomerase meet! , 1997, Journal of cell science.

[2]  A. Nicolas,et al.  An atypical topoisomerase II from archaea with implications for meiotic recombination , 1997, Nature.

[3]  P. Forterre,et al.  DNA topology in hyperthermophilic archaea: reference states and their variation with growth phase, growth temperature, and temperature stresses , 1997, Molecular microbiology.

[4]  J. DiRuggiero,et al.  Characterization of the reverse gyrase from the hyperthermophilic archaeon Pyrococcus furiosus , 1997, Journal of bacteriology.

[5]  A. Maxwell,et al.  Conversion of DNA gyrase into a conventional type II topoisomerase. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[6]  C. Jaxel,et al.  Reverse gyrase gene from Sulfolobus shibatae B12: gene structure, transcription unit and comparative sequence analysis of the two domains. , 1996, Nucleic acids research.

[7]  P. Forterre,et al.  A gyrB-like gene from the hyperthermophilic bacterion Thermotoga maritima. , 1996, Gene.

[8]  P. Forterre,et al.  DNA topological change in the hyperthermophilic archaeon Pyrococcus abyssi exposed to low temperature , 1996 .

[9]  P. Forterre,et al.  The unique DNA topology and DNA topoisomerases of hyperthermophilic archaea. , 1996, FEMS microbiology reviews.

[10]  A. Slesarev,et al.  A two-subunit type I DNA topoisomerase (reverse gyrase) from an extreme hyperthermophile. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[11]  R. Huber,et al.  Cloning and sequencing of the gene coding for topoisomerase I from the extremely thermophilic eubacterium, Thermotoga maritima. , 1995, Biochimica et biophysica acta.

[12]  K. S. Yip,et al.  The structure of Pyrococcus furiosus glutamate dehydrogenase reveals a key role for ion-pair networks in maintaining enzyme stability at extreme temperatures. , 1995, Structure.

[13]  R. Sterner,et al.  (Beta alpha)8‐barrel proteins of tryptophan biosynthesis in the hyperthermophile Thermotoga maritima. , 1995, The EMBO journal.

[14]  R. Huber,et al.  A cryptic miniplasmid from the hyperthermophilic bacterium Thermotoga sp. strain RQ7 , 1994, Journal of bacteriology.

[15]  P. Forterre,et al.  Comparison of plasmid DNA topology among mesophilic and thermophilic eubacteria and archaebacteria , 1994, Journal of bacteriology.

[16]  Leroy F. Liu.  DNA Topoisomerases : Topoisomerase-targeting drugs , 1994 .

[17]  C. Schleper,et al.  The DNA-dependent RNA-polymerase of Thermotoga maritima; characterisation of the enzyme and the DNA-sequence of the genes for the large subunits. , 1993, Nucleic acids research.

[18]  P. Forterre,et al.  Reverse gyrase: a helicase-like domain and a type I topoisomerase in the same polypeptide. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[19]  P. Forterre,et al.  Evidence that a plasmid from a hyperthermophilic archaebacterium is relaxed at physiological temperatures , 1992, Journal of bacteriology.

[20]  A. Wolffe,et al.  DNA gyrase, CS7.4, and the cold shock response in Escherichia coli , 1992, Journal of bacteriology.

[21]  K. Stetter,et al.  DNA topoisomerase III from extremely thermophilic archaebacteria. ATP-independent type I topoisomerase from Desulfurococcus amylolyticus drives extensive unwinding of closed circular DNA at high temperature. , 1991, The Journal of biological chemistry.

[22]  R. Huber,et al.  Reverse gyrase in thermophilic eubacteria , 1991, Journal of bacteriology.

[23]  R. J. Reece,et al.  The C-terminal domain of the Escherichia coli DNA gyrase A subunit is a DNA-binding protein. , 1991, Nucleic acids research.

[24]  M. Dyall-Smith,et al.  Mutations in DNA gyrase result in novobiocin resistance in halophilic archaebacteria , 1991, Journal of bacteriology.

[25]  P. Forterre,et al.  Novobiocin induces positive supercoiling of small plasmids from halophilic archaebacteria in vivo. , 1988, Nucleic acids research.

[26]  J. Wang,et al.  Supercoiling of the DNA template during transcription. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[27]  A. Kikuchi,et al.  Reverse gyrase—a topoisomerase which introduces positive superhelical turns into DNA , 1984, Nature.

[28]  D. Lockshon,et al.  Positively supercoiled plasmid DNA is produced by treatment of Escherichia coli with DNA gyrase inhibitors. , 1983, Nucleic acids research.

[29]  L. J. Peck,et al.  DNA supercoiling and its effects on DNA structure and function. , 1983, Cold Spring Harbor symposia on quantitative biology.

[30]  W. Staudenbauer,et al.  DNA gyrase: affinity chromatography on novobiocin-Sepharose and catalytic properties. , 1981, Nucleic acids research.

[31]  N. Cozzarelli.  DNA gyrase and the supercoiling of DNA. , 1980, Science.

[32]  J. Wang,et al.  Micrococcus luteus DNA gyrase: active components and a model for its supercoiling of DNA. , 1978, Proceedings of the National Academy of Sciences of the United States of America.

[33]  J. Wang,et al.  Conformational fluctuations of DNA helix. , 1975, Proceedings of the National Academy of Sciences of the United States of America.

[34]  J Cairns,et al.  Cold Spring Harbor Symposia. , 1968, Science.