The following text describes a protein:
Function:
Modifies the topological state of DNA by introducing positive supercoils in an ATP-dependent process (Probable). A highly processive enzyme, it introduces a large number of positive supercoils directly in a negatively supercoiled substrate. At 75 degrees Celsius introduces more than 23 positive supercoils into pTZ18R DNA (probably 2860 bp), more than TopR1; unlike TopR1 little to no relaxation of the negatively supercoiled substrate is seen in the presence of ATP, in the absence of ATP no activity is seen. At 45 degrees Celsius the enzyme is slower and in vitro individual steps can be detected. It cleaves transiently a single DNA strand and remains covalently bound to the 5' DNA end through a tyrosine residue (Probable). May be involved in DNA damage response (Probable). May be involved in rewinding the DNA strands in the regions of the chromosome that have opened up to allow transcription or replication; There are 2 genes for this protein in the cell. During exponential growth this is the more highly expressed isoform (about 125 molecules per cell at 80 degrees Celsius, about 117 molecules at 88 degrees Celsius); this isoform is less active at higher temperature. Grows actively at both 80 and 88 degrees Celsius; survives a long exposure at 45 degrees Celsius without DNA replication or cell division occurring. Experiments using whole cell extracts do not distinguish which isoform is present, the results are probably a mixture of the two forms (Probable).
Miscellaneous:
MISCELLANEOUS: This enzyme is the only unique feature of hyperthermophilic bacteria/archaea known and seems to be essential for adaptation to life at high temperatures. It may play a role in stabilization of DNA at high temperatures; MISCELLANEOUS: Strain 2-2-12 is a substrain of P2 that is highly susceptible to infection by Sulfolobus turreted icosahedral virus 1 (STIV-1).
Subcellular Localization:
Cytoplasm. Note=Upon UV irradiation up to 60% of the reverse gyrase activity becomes associated with DNA in vivo.
Domain:
Both the DNA unwinding and positive supercoiling activities require the cooperation of both domains. The cooperative action between the helicase-like and the topoisomerase domains is specific. The helicase-like domain probably does not directly unwind DNA but acts more likely by driving ATP-dependent conformational changes within the whole enzyme, functioning more like a protein motor. The 'latch' region of the N-terminal domain plays a regulatory role in the enzyme, repressing topoisomerase activity in the absence of ATP and therefore preventing the enzyme from acting as an ATP-independent relaxing enzyme; it also helps to coordinate nucleotide hydrolysis by the ATPase domain with the supercoiling activity of the topoisomerase domain.
Sequence:
MINVMYKNSCPNCGGDISGDRLLNGLPCEACLPYINGIDDVDHISKVKTLYNILLNNDKIKNYWNLYYNITTFETVFKYFRDKTGYEPWSLQKLWLRRLASNQSFTMSAPTGLGKTTTLMTYSVFIGQDVVYIVPTKSLMEQVCKRLEKLGAQVSCGKIDQKKVSVITISYLNKNADSIVSLKPNFVVIDDADAVIKSGKTTDRLVSLLGIPKDVYESAIQLIRLRNKYYFSNEYTEEVKEKIRELELKIAEFKDKISQLVIASATIRPKGIKQKALRLLTGFEPSSIQLYARNIIDAYTENLDLSIVKELGSGGLILVSKEYGRSKLNEIKKYVEDLGFNAKLAISGRKFLDDFSQGKVDILVGSASYYGVAVRGIDEPKRLKYVIYYGVPKIRAKLFDALSNPFTLLRVGKLIGIDFSKLQNKILILNPSEVQLLKFSIIKGESINYHKLEQLRQELLYYMSLVKDKLKEKVEDTLISDSFVITKQNGNYYIVYPDMITYLQGSGRASRLYNGGLTLGFSIILVDDRHIFEILEKKMQKLFPNTTFTSLSNTNLSEIKIKLEDSRKEEGNRVHFNISTGLLIVESPTKAKTIAKMFSRPSVRIRNKVPVYETIIVDGNQIYVLDIVASKGHIVDLTLEDIGYYGIKVEDDGTIKPYYDLIKKCLDCNKIFSSASDKCPYCGSANLQSAQTTINLLRELALSVDKVFIASDPDTEGEKIAYDLASFLSPYNSNVYRVVYHEITKKAILEALRNPKKINTNLVMSQIVRRIEDRWIGFTLSNLLKTKFNGHNHGAGRVQTPVLGWIVNKTIKYKSAMGHVVYIDIAGYSIKKYFSEKRKVEEYINNLQVARIEKISEEKILLSPLPPFTTDTLLIEANMKYKLPANLVMKIAQDLFEAGLITYHRTDSTHISSVGIEIAKEYLQKQALIKEFVPRSWESSEEGAHEAIRPTRAIDVNELIQEIEENPYKYSIRFSKLHLLIYDLIFKRFIASQMSHAVGTKSRYLIKLGKDDNVDVELLSNAEGGFIKVYPVKVYNLPVGEIQPKVNITKGSSEQLLSYSDVISLMKSKGIGRPSTYAKTIENLMKHGYIVSSKRKSYLIATNRGISVYQFLSSKFYDLVSESTTSRLMTKLDDIALSKLNASTVLLEIFSEISTLVNPLKSEQNV