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 gyraselike enzyme have been cloned and sequenced. The Top2A (type II DNA topoisomerase A p...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1997-09, Vol.94 (20), p.10606-10611
Main Authors: Guipaud, Olivier, Marguet, Evelyne, Noll, Kenneth M., De La Tour, Claire Bouthier, Forterre, Patrick
Format: Article
Language:English
Subjects:
Archaea
Bacteria
Bacteriology
Biochemistry
Biological Sciences
Cloning, Molecular
Deoxyribonucleic acid
DNA
DNA Topoisomerases, Type II - genetics
DNA Topoisomerases, Type II - metabolism
DNA, Bacterial - chemistry
DNA, Bacterial - drug effects
DNA, Superhelical - chemistry
DNA, Superhelical - drug effects
Enzymes
Gels
Genomics
Gram-Negative Anaerobic Bacteria - enzymology
Mathematical topoi
Molecular Sequence Data
Novobiocin - pharmacology
Plasmids
Proteins
Thermotoga maritima
Topology
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Summary: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 gyraselike 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.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.94.20.10606