The following text describes a protein:
Function:
Modifies the topological state of DNA by introducing positive supercoils in an ATP-dependent process, increasing the linking number in steps of +1. Binds to single-stranded DNA, transiently cleaves and then rejoins the ends, introducing a positive supercoil in the process. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate. Involved in rewinding DNA strands in regions of the chromosome that have opened up to allow replication, transcription, DNA repair and/or for DNA protection; Modifies the topological state of DNA by introducing positive supercoils in an ATP-dependent process, increasing the linking number in steps of +1. Binds to single-stranded DNA, transiently cleaves and then rejoins the ends, introducing a positive supercoil in the process. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate. Probably involved in rewinding DNA strands in regions of the chromosome that have opened up to allow replication, transcription, DNA repair and/or for DNA protection.
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.
Subcellular Localization:
Cytoplasm.
Domain:
Introduction of positive supercoils requires the cooperation of both domains. The helicase-like domain probably does not directly unwind DNA, but more likely acts by driving ATP-dependent conformational changes within the whole enzyme. A beta hairpin in the 'latch' region of the N-terminal domain plays a regulatory role in the enzyme, repressing topoisomerase activity in the absence of ATP and 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:
MIEAIFKNLCPNCGGDIASERLLAGLLCEKCLPKEVPQEVLCNHIKEEDYDLCSLKKKYGEWERVFKSFVGFEPWELQKFWAKKLLLGRSFALLAPTGIGKTSWGLATSLYFAKKNKKSYIILPTKLLILQSYEKLKDKIREEDLLVFGLDDTKKEKEEKRERLEKGDFKVLITSSMFLYKNVDIIPKDFGFVFVDDVDSFLKTAKNIDKALYLLGFSEEDINLTMSYIRMRKNGEEEVKRMQEEVRKIAKKAKGVMVVSSATSNPKSERIRLFKELLAFDVGRPVFYLRNVEDIYEEVEDLNKTLVERVKRLGKGGLVFLSSDFGKEYVDEVKNLLINEGISAESYDNLTPEVLEKYQKGEIFVLIGISSYRNPLARGLDLPEVIRYAIFYGVPKIVVNLDLEGNVRHLLIALASIRPLVARDKNLEKHVANLDRWMKTLKRYSSMLNPPRDKVEELRNIIKAFILSPEVYEKIKSADDIAIREENGKWVLVVSDITGYLQASGRTSRLYVGGISKGLSYILVEDKKVFNNLVRKSRWWFSTDIIFKESNTVNLDEILKQIDEDREKIRKKEGRRDDFLKPVLVIVESPHKAWTIANFFGRPISRNVNGQELFEVITEDKYLVITASFGHILDLNKEIGYYGVIENGKFIPVYEPIEGKEKIISGIRDASKEFEMILVATDPDTEGEKISWDLKNLCSPFTKEIRRMEFHEVTKKAILNSLKEYRDVDENLVKAQVVRRISDRWVGFELSQLIQRIFYKNYLSAGRVQTPVLGWVIERAKENKKRVYLVLIKKDGLDLRFEFENKDEAQKFYNELKYIEVTKETEKVEEKSPLPPYTTDAVLKDASDRFKLSVSRTMEVLQELFERGFITYHRTDSTRVSDTGINVAREYINEQFGEEYFRGRTWGEGGAHECIRPTRVLDVEDIKAMIYSGELEGFTPDHLKIYDLVFKRFIASQMRNVILRGYEVLVKAIDKEQKLDVYEEVVQNGFDKIFPIKLAKIPEGEIDVVNNKFFYSIPKVPLFTQGSLVEEMKKRGLGRPSTYATIVSRLLERGYVIEKNGYLIPTPLGEKVYQYLNSDQEKFRFVREDFTRELEELMDKVENGERDYQEILKSLRNELEKV