>TIGR01054 rgy reverse gyrase; InterPro: IPR005736 DNA topoisomerases regulate the number of topological links between two DNA strands (i.e. change the number of superhelical turns) by catalysing transient single- or double-strand breaks, crossing the strands through one another, then resealing the breaks. These enzymes have several functions: to remove DNA supercoils during transcription and DNA replication; for strand breakage during recombination; for chromosome condensation; and to disentangle intertwined DNA during mitosis , . DNA topoisomerases are divided into two classes: type I enzymes (5.99.1.2 from EC; topoisomerases I, III and V) break single-strand DNA, and type II enzymes (5.99.1.3 from EC; topoisomerases II, IV and VI) break double-strand DNA . Type I topoisomerases are ATP-independent enzymes (except for reverse gyrase), and can be subdivided according to their structure and reaction mechanisms: type IA (bacterial and archaeal topoisomerase I, topoisomerase III and reverse gyrase) and type IB (eukaryotic topoisomerase I and topoisomerase V). These enzymes are primarily responsible for relaxing positively and/or negatively supercoiled DNA, except for reverse gyrase, which can introduce positive supercoils into DNA. Reverse gyrase is a type IA topoisomerase that is unique among these enzymes in its requirement for ATP. Reverse gyrase is a hyperthermophile-specific enzyme that acts as a renaturase by positively supercoiling DNA, and by annealing complementary single-strand circles . Hyperthermophilic organisms must protect themselves against heat-induced degradation, and reverse gyrase acts to reduce the rate of double-strand DNA breakage, a function that does not require ATP hydrolysis and which is independent of its positive supercoiling abilities. Reverse gyrase achieves this by recognising nicked DNA and recruiting a protein coat to the site of damage . More information about this protein can be found at Protein of the Month: DNA Topoisomerase .; GO: 0003677 DNA binding, 0003916 DNA topoisomerase activity, 0006265 DNA topological change, 0006268 DNA unwinding during replication, 0005694 chromosome.

Probab=98.49  E-value=7.7e-07  Score=71.41  Aligned_cols=114  Identities=26%  Similarity=0.451  Sum_probs=83.7

Q ss_pred             HHHHHHHHHHHHHHCCCCCEEEEECCCCHHHHHHHHHHHHHHHHC--CCCEEEEECCCHHHHHHHHHHHCCC---C--CE
Q ss_conf             378999999987520489619984475315799999999998514--6847997152100134455543038---9--76
Q gi|254780619|r  201 KNQQDVVEQVVPLCTKGFAVSLISGVTGSGKTEVYLEIVAAVLHL--GKQVLILLPEISLTSAILERFQKRF---G--VK  273 (731)
Q Consensus       201 ~eQ~~a~~~i~~~~~~~f~~~LL~GvTGSGKTEVYl~li~~~L~~--GkqvLiLvPEI~Lt~Q~~~rl~~rF---~--~~  273 (731)
T Consensus        87 s~Qk~WAKRv~~--~~SF---ai~APTGVGKttFG-~~mslflA~kKGkR~y~ilPT~lLv~Qv~~kl~~~~~k~g~~~~  160 (1843)
T TIGR01054        87 SIQKSWAKRVLK--GDSF---AIVAPTGVGKTTFG-LVMSLFLAKKKGKRSYIILPTTLLVKQVAEKLSSLAEKEGVGIV  160 (1843)
T ss_pred             HHHHHHHHHHHC--CCCE---EEECCCCCCHHHHH-HHHHHHHHHHCCCEEEEEECHHHHHHHHHHHHHHHCCCCCCCCE
T ss_conf             567999999641--7964---89805887677999-99999986542987899947078899999998752002575000


Q ss_pred             --EEEEECCCCCHHHHHHHHHHHCCCCEEEEECCHHHHH-------H-HCCCEEEEEEE
Q ss_conf             --8996235572356678999971997399940012110-------0-10001367740
Q gi|254780619|r  274 --PAEWHSSLSTSMREKIWRQVARGAISVIVGVRSALFL-------P-FKKLGLIVIDE  322 (731)
Q Consensus       274 --v~v~HS~ls~~eR~~~w~~i~~G~~~IVIGtRSAif~-------P-~~nLglIIvDE  322 (731)
T Consensus       161 ~l~~~yhS~L~~~~kke~~Eri~~GDfdilitT--~~FL~K~~~~L~~~y~F~liFVDD  217 (1843)
T TIGR01054       161 RLLGAYHSKLSTKEKKEVKERIENGDFDILITT--SMFLSKNFDKLKNQYKFDLIFVDD  217 (1843)
T ss_pred             EEEEEEECCCCHHHHHHHHHHHHCCCEEEEHHH--HHHHHHHHHHCCCCCEEEEEEEEC
T ss_conf             022210112654567889998731891786122--468887665178985144899715