Sulfolobus reverse gyrase

In their first paper, Kikuchi and Asai [72] reported that S. acidocaldarius contained, besides a reverse gyrase, one ATP-independent and two ATP-dependent thermophilic DNA topoisomerases (including one DNA gyrase). However, their purification procedure lacked a step to remove DNA, so that at least one of the ATP-dependent topoisomerases probably corresponded to the reverse gyrase copurifying with DNA (discussed in ref [74]). Later work did not confirm the presence of a classical gyrase but demonstrated the presence of at least one type II DNA topoisomerase, and probably one ATP-independent type I DNA topoisomerase in Sulfolobus and in other thermophilic archaebacteria. 

The first gene encoding a reverse gyrase, TopR, was cloned by screening a Agt 11 expression library of Sulfolobus acidocaldarius genomic DNA, with polyclonal... 

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