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	Gyrase - Wikipedia, the free encyclopedia
		DNA gyrase, often referred to simply as gyrase, is a type II topoisomerase (EC 5.99.1.3) that introduces negative supercoils (or relaxes positive supercoils) into DNA by generating a loop in the template, cutting one of the strands and passing one over the other, changing the linking number by two in each enzymatic step
		The right-handed nature of the DNA double helix causes positive supercoils to accumulate ahead of a translocating enzyme, in the case of DNA replication, a DNA polymerase.
		DNA gyrase is a member of a class of enzymes called topoisomerases.
	en.wikipedia.org /wiki/DNA_gyrase (316 words)

	DNA Gyrase in vitro activity
		DNA Gyrase is a type II topoisomerase that catalyses transient doublestrand breaks and uses free energy of ATP hydrolysis for introducing negative supercoils into DNA molecules by reducing the helix-linking number in steps of 2.
		It was shown that both Gyrase activity in vitro and DNA supercoiling mediated by Gyrase and topoisomerase I in vivo depend on ATP/ADP ratios (van Workum, 1996; Westerhoff, 1988) and that DNA supercoiling influences the expression of Gyrase and topoisomerase I in E.coli (Menzel and Gellert, 1983; Tse-Dinh, 1985).
		Gyrase also shows a so called slippage effect, that means, ATP hydrolysis is coupled to supercoiling activity to a rather variable extent (Westerhoff, 1988).
	home.arcor.de /uscho/projekte/gyrase.htm (396 words)

	DNA Topoisomerases (Site not responding. Last check: 2007-10-31)
		DNA topoisomerases are enzymes that control and modify the topological states of DNA in cells.
		Bacterial DNA gyrase is a type II DNA topoisomerase which catalyses the negative supercoiling of prokaryotic DNA, utilising the free energy released by the hydrolysis of ATP.
		DNA gyrase is the target of two classses of antibiotic drugs: the quinolones and the coumarins.
	www.icnet.uk /labs/wigley/projects/topoisomerase/topoisomerase.html (331 words)

	DNA Structure, Replication and Eukaryotic Chromatin Structure>
		DNA replication is semi-conservative, one strand serves as the template for the second strand.
		DNA single-stranded binding proteins - These proteins bind to the DNA as a tetramer and stabilize the single-stranded structure that is generated by the action of the helicases.
		The DNA molecule is unwound and prepared for synthesis by the action of DNA gyrase, DNA helicase and the single-stranded DNA binding proteins.
	www.ndsu.nodak.edu /instruct/mcclean/plsc431/eukarychrom/eukaryo2.htm (727 words)

	DNA replication - EvoWiki (Site not responding. Last check: 2007-10-31)
		This mechanism for DNA replication is known as the semiconservative model.
		An enzyme called DNA helicase unwinds the DNA, while DNA gyrase assists in preventing the DNA from falling appart while it is in the unstable uncoiled state.
		The Replication of DNA in Cold Spring Harb Symp Quant Biol, 1958;23:9-12.
	wiki.cotch.net /index.php/DNA_replication (369 words)

	Molecular Characterization of the Gene Encoding the DNA Gyrase A Subunit of Streptococcus pneumoniae -- Balas et al. ...
		The gene encoding the DNA gyrase A subunit of Streptococcus pneumoniae was cloned and sequenced.
		DNA supercoiling is known to influence the curvature of DNA (33).
		Ser-127-to-Leu substitution in the DNA gyrase B subunit of Streptococcus pneumoniae is implicated in novobiocin resistance.
	jb.asm.org /cgi/content/full/180/11/2854 (4193 words)

	Cloning and Nucleotide Sequence of the DNA Gyrase (gyrA) Gene from Mycoplasma hominis and Characterization of ...
		Molecular characterization of the gene encoding the DNA gyrase A subunit of Streptococcus pneumoniae.
		Streptococcus pneumoniae DNA gyrase and topoisomerase IV: overexpression, purification, and differential inhibition by fluoroquinolones.
		Nucleotide sequence and molecular characterization of the DNA gyrase genes from Clostridium acetobutylicum.
	aac.asm.org /cgi/content/full/44/10/2719 (3636 words)

	Pfam 20.0 : DNA_gyraseB_C (Site not responding. Last check: 2007-10-31)
		The amino-terminal portion of the DNA gyrase B protein is thought to catalyse the ATP-dependent super-coiling of DNA.
		DNA topoisomerases are divided into two classes: type I enzymes (; topoisomerases I, III and V) break single-strand DNA, and type II enzymes (; topoisomerases II, IV and VI) break double-strand DNA PUBMED:12596227.
		Topoisomerase IV primarily decatenates DNA and relaxes positive supercoils, which is important in bacteria, where the circular chromosome becomes catenated, or linked, during replication PUBMED:16023670.
	pfam.wustl.edu /cgi-bin/getdesc?name=DNA_gyraseB_C (415 words)

	Crystal structure of reverse gyrase: insights into the positive supercoiling of DNA
		We cloned the reverse gyrase gene from the hyperthermophilic archaeon Archaeoglobus fulgidus and overexpressed it in E.coli.
		DNA binds to the protein and the latch (subdomain H3) intercalates between the strand to be cleaved and the strand to be passed, such that the scissile strand lies on the side facing subdomain T3.
		Reverse gyrase was cloned by PCR using genomic DNA from A.fulgidus (DSMZ) and overexpressed in pRET3a (Tan et al., 2000) in E.coli C41(DE3) (Miroux and Walker, 1996).
	www.nature.com /emboj/journal/v21/n3/full/7594262a.html (5049 words)

	DNA gyrases (Site not responding. Last check: 2007-10-31)
		DNA gyrase from Thermotoga maritima - a combination of extreme conformational flexibility and thermostability
		Patrick Forterre in Paris we focus on the DNA gyrase from this organism.
		Gyrase is a type II DNA topoisomerase which introduces supercoils into DNA by catalyzing the breakage of a first double-stranded DNA molecule, the passage of a second DNA duplex through this gap and the religation of the first DNA molecule in an ATP-dependent manner.
	www.csb.ki.se /users/xray/gyrases.html (176 words)

	nitworks notes (Site not responding. Last check: 2007-10-31)
		DNA gyrase, also called gyrase, is an enzyme in the topoisomerase family that passes one double strand of DNA through another double strand of DNA.
		Because gyrase changes the linking number of the DNA by two in each enzymatic step, it is classified as a type II topoisomerase.
		Gyrase is only found in bacteria; it is not found in eukaryotes, a property that makes gyrase a good target for antibiotics.
	www.nitworks.com /notes (1758 words)

	Mechanochemical analysis of DNA gyrase using rotor bead tracking : Nature
		DNA gyrase is a molecular machine that uses the energy of ATP hydrolysis to introduce essential negative supercoils into DNA
		In the presence of gyrase and ATP, we observe bursts of rotation corresponding to the processive, stepwise introduction of negative supercoils in strict multiples of two
		Changes in DNA tension have no detectable effect on supercoiling velocity, but the enzyme becomes markedly less processive as tension is increased over a range of only a few tenths of piconewtons.
	www.nature.com /nature/journal/v439/n7072/abs/nature04319.html (412 words)

	DNA Replication & Repair
		Handout: Enzymes & Proteins that act on DNA is a worksheet to accompany this lecture.
		Thus, the enzymes involved, the accessory proteins required, and the DNA structures they work on have been conserved in evolution from viruses, to bacteria, to yeast, to fruit flys, to humans.
		In other words, the balance between the speed and accuracy of DNA replication in any organism is an optimization that has been adjusted by natural selection.
	www.nitorig.net /lec18.html (1291 words)

	PHRI :: Karl Drlica, Ph.D.
		The fluoroquinolones trap DNA gyrase and DNA topoisomerase IV on bacterial DNA as ternary complexes that rapidly block DNA replication.
		Mutation in the DNA gyrase A Gene of Escherichia coli that expands the quinolone resistance-determining region.
		Heddle JG, Lu T, Zhao X, Drlica K, Maxwell A. gyrB-225, a mutation of DNA gyrase that compensates for topoisomerase I deficiency: investigation of its low activity and quinolone hypersensitivity.
	www.phri.org /research/res_pidrlica.asp (1892 words)

	Pfam 20.0 : DNA_gyraseB (Site not responding. Last check: 2007-10-31)
		This entry represents the second domain found in subunit B (gyrB and parE) of bacterial gyrase and topoisomerase IV, and the equivalent N-terminal region in eukaryotic topoisomerase II composed of a single polypeptide.
		Crystal structure of an N-terminal fragment of the DNA gyrase B protein.
		Isoleucine 10 is essential for DNA gyrase B function in Escherichia coli.
	pfam.wustl.edu /cgi-bin/getdesc?name=DNA_gyraseB (499 words)

	Active-Site Residues of Escherichia coli DNA Gyrase Required in Coupling ATP Hydrolysis to DNA Supercoiling and Amino ...
		Novobiocin and coumermycin inhibit DNA supercoiling catalyzed by DNA gyrase.
		Probing the role of the ATP-operated clamp in the strand-passage reaction of DNA gyrase.
		Locking the ATP-operated clamp of DNA gyrase: probing the mechanism of strand passage.
	aac.asm.org /cgi/content/full/47/3/1037 (6599 words)

	martin bormann dna test - dna paternity testing advice
		Although an estimated 200,000 DNA tests are conducted each year by states needing to sort child-support and welfare issues, few people are willing to conduct their own at-home paternity test.
		DNA kits can also be used to analyze siblingship, establish cousin or grandparent relationships, determine twin zygosity (i.e.
		In 1999, a DNA test was done on it which confirmed the...
	www.dnatestme.com /martinbormanndnatest (1234 words)

	Computational Analysis of DNA Gyrase Action -- Vologodskii 87 (5): 3066 -- Biophysical Journal
		DNA gyrase is a bacterial enzyme that introduces negative supercoiling
		Micrococcus luteus DNA gyrase: active components and a model for its supercoiling of DNA.
		Wang, J. Moving one DNA double helix through another by a type II DNA topoisomerase: the story of a simple molecular machine.
	www.biophysj.org /cgi/content/full/87/5/3066 (3858 words)

	The interaction of DNA gyrase with microcin B17
		DNA gyrase from Arabidopsis thaliana: its role in organellar replication
		We have discovered that the model plant Arabidopsis thaliana encodes the DNA supercoiling enzyme DNA gyrase, an enzyme previously thought to be unique to bacteria.
		Results so far suggest that there are at least two gyrases, one that is specific to mitochondria and one specific to plastids (chloroplasts).
	www.gla.ac.uk /ibls/US/bursary/dnagyrase.htm (145 words)

	Locking the DNA Gate of DNA Gyrase: Investigating the Effects on DNA Cleavage and ATP Hydrolysis (Site not responding. Last check: 2007-10-31)
		Supercoiling by DNA gyrase involves the passage of one segment of double-stranded DNA through another.
		This requires a DNA duplex to be cleaved and the broken ends separated by at least 20 Å.
		This is accomplished by the opening of a dimer interface, termed the DNA gate, which is covalently attached to the broken ends of the DNA.
	pubs.acs.org /cgi-bin/abstract.cgi/bichaw/1999/38/i43/abs/bi991478m.html (189 words)

	Gyrase 2000G
		Incubation of 1 µg of catenated KDNA or supercoiled pUC19 DNA for 4 hrs.
		One unit of gyrase activity will supercoil 0.25 ug pBR-322 DNA in 30 min at 37 C. A 5X assay buffer and dilution buffer is included with the enzyme.
		The enzyme is shipped on dry ice and should be stored at -70 C. We also recommend that the enzyme be aliquoted after the first thaw (repeated rounds of freeze/thaw may cause loss of activity); the enzyme activity is stable for 1-3 days on ice.
	www.topogen.com /html/gyrase.html (295 words)

	302 Lecture Topic: Replication
		In replication, the original DNA strand is used as a template.
		DNA synthesis goes 5' to 3' on the new strand of DNA.
		After the new DNA has replicated, the chromosomes attach to the cell wall and are pulled apart.
	www.science.siu.edu /microbiology/micr302/replication.html (312 words)

	Inhibitory activity of quinolones against DNA gyrase of Mycobacterium tuberculosis -- Onodera et al. 47 (4): 447 -- ...
		Relaxed pBR322 DNA was incubated with GyrA and GyrB proteins in the absence or presence of the drug.
		Guillemin, I., Jarlier, V. and Cambau, E. Correlation between quinolone susceptibility patterns and sequences in the A and B subunits of DNA gyrase in mycobacteria.
		Guillemin, I., Sougakoff, W., Cambau, E., Viravau, V. R., Moreau, N. and Jarlier, V. Purification and inhibition by quinolones of DNA gyrase from Mycobacterium avium, Mycobacterium smegmatis and Mycobacterium fortuitum bv.
	jac.oxfordjournals.org /cgi/content/full/47/4/447 (1909 words)

	Arabidopsis thaliana DNA gyrase is targeted to chloroplasts and mitochondria -- Wall et al. 101 (20): 7821 -- ...
		DNA gyrase is the bacterial DNA topoisomerase (topo) that supercoils
		DNA gyrase is a type II enzyme that is essential for the processes of replication and
		Sequence and Phylogenetic Analyses of A. thaliana Gyrase Genes.
	www.pnas.org /cgi/content/full/101/20/7821 (4157 words)

	DNA Gyrase Genes in Mycobacterium tuberculosis: a Single Operon Driven by Multiple Promoters -- Unniraman et al. 184 ...
		Discoordinate gene expression of gyrA and gyrB in response to DNA gyrase inhibition in Escherichia coli.
		Interplay of novobiocin-resistant and -sensitive DNA gyrase activities in self-protection of the novobiocin producer Streptomyces sphaeroides.
		Regulation of DNA gyrase operon in Mycobacterium smegmatis: a distinct mechanism of relaxation stimulated transcription.
	jb.asm.org /cgi/content/full/184/19/5449 (2866 words)

	A Superhelical Spiral in the Escherichia coli DNA Gyrase A C-terminal Domain Imparts Unidirectional Supercoiling Bias ...
		DNA gyrase is unique among type II topoisomerases in that its
		coli GyrA-CTD to impart right-handed superhelicity on the DNA.
		By enforcing the (+) node as a DNA substrate requirement for gyrase, the GyrA-CTD is responsible for (+) supercoil relaxation and () supercoil induction.
	www.jbc.org /cgi/content/full/280/28/26177 (4600 words)

	Roles of topoisomerase IV and DNA gyrase in DNA unlinking during replication in Escherichia coli -- Zechiedrich and ...
		Roles of topoisomerase IV and DNA gyrase in DNA unlinking during replication in Escherichia coli -- Zechiedrich and Cozzarelli 9 (22): 2859 -- Genes and Development
		Roles of topoisomerase IV and DNA gyrase in DNA unlinking during replication in Escherichia coli
		DNA Gyrase-mediated Wrapping of the DNA Strand Is Required for the Replication Fork Arrest by the DNA Gyrase-Quinolone-DNA Ternary Complex
	www.genesdev.org /cgi/content/abstract/9/22/2859 (1587 words)

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