DNAgyraasi ja Borrelia

https://www.ncbi.nlm.nih.gov/pubmed/?term=DNAgyrase%2C+borrelia

Search results

Items: 15

• Showing results for dna gyrase, borrelia. Search instead for DNAgyrase, borrelia (0)

Select item 158971981.

A superhelical spiral in the Escherichia coli DNA gyrase A C-terminal domain imparts unidirectional supercoiling bias.

Ruthenburg AJ, Graybosch DM, Huetsch JC, Verdine GL.

J Biol Chem. 2005 Jul 15;280(28):26177-84. Epub 2005 May 15.

DNA gyrase is unique among type II topoisomerases in that its DNA supercoiling activity is unidirectional. The C-terminal domain of the gyrase A subunit (GyrA-CTD) is required for this supercoiling bias. We report here the x-ray structure of the Escherichia coli GyrA-CTD (Protein Data Bank code 1ZI0). The E. coli GyrA-CTD adopts a circular-shaped beta-pinwheel fold first seen in the Borrelia burgdorferi GyrA-CTD. However, whereas the B. burgdorferi GyrA-CTD is flat, the E. coli GyrA-CTD is spiral. DNA relaxation assays reveal that the E. coli GyrA-CTD wraps DNA inducing substantial (+) superhelicity, while the B. burgdorferi GyrA-CTD introduces a more modest (+) superhelicity. The observation of a superhelical spiral in the present structure and that of the Bacillus stearothermophilus ParC-CTD structure suggests unexpected similarities in substrate selectivity between gyrase and Topo IV enzymes. We propose a model wherein the right-handed ((+) solenoidal) wrapping of DNA around the E. coli GyrA-CTD enforces unidirectional (-) DNA supercoiling.Free Article

Similar articles

https://www.researchgate.net/figure/7720486_fig1_Figure-1-Reactions-catalyzed-by-DNA-gyrase-and-topoisomerase-IV-a-Representative-DNA


 

Select item 127911462.

Transcriptional regulation of the ospAB and ospC promoters from Borrelia burgdorferi.

Alverson J, Bundle SF, Sohaskey CD, Lybecker MC, Samuels DS.

Mol Microbiol. 2003 Jun;48(6):1665-77.

OspA, OspB and OspC are the major outer surface proteins of Borrelia burgdorferi that are differentially synthesized in response to environmental conditions, including culture temperature. We found that DNA was more negatively supercoiled in B. burgdorferi cultures grown at 23 degrees C compared with cultures grown at 35-37 degrees C. We examined the regulation of ospAB and ospC transcription by temperature and DNA supercoiling. DNA supercoiling was relaxed by adding coumermycin A1, an antibiotic that inhibits DNA gyrase. Syntheses of the major outer surface proteins, expression of the ospA and ospC genes and the activities of the ospAB operon and ospC gene promoters were assayed. ospA product levels decreased, whereas ospC product levels increased after shifting from 23 degrees C to 35 degrees C or after adding coumermycin A1. In addition, OspC synthesis was higher in a gyrB mutant than in wild-type B. burgdorferi. Promoter activity was quantified using cat reporter fusions. Increasing temperature or relaxing supercoiled DNA resulted in a decrease in ospAB promoter activity in B. burgdorferi, but not in Escherichia coli, as well as an increase in ospC promoter activity in both bacteria. ospC promoter activity was increased in an E. coli gyrB mutant with an attenuated DNA supercoiling phenotype. These results suggest that B. burgdorferi senses environmental changes in temperature by altering the level of DNA supercoiling, which then affects the expression of the ospAB operon and the ospC gene. This implies that DNA supercoiling acts as a signal transducer for environmental regulation of outer surface protein synthesis.Free Article

Similar articles
 

Select item 123748433.

groEL expression in gyrB mutants of Borrelia burgdorferi.

Alverson J, Samuels DS.

J Bacteriol. 2002 Nov;184(21):6069-72.

GroEL protein and groEL mRNA transcript were up-regulated in gyrB mutants of Borrelia burgdorferi, a causative agent of Lyme disease. Furthermore, the protein and transcript levels in gyrB mutants were greater than those in experimentally heat-shocked cultures of wild-type B. burgdorferi. Circular DNA in the gyrB mutants was more relaxed than in wild-type cells, although groEL is on the linear chromosome of B. burgdorferi. To our knowledge, this is the first evidence, albeit indirect, for the effect of DNA topology on gene expression from a linear DNA molecule in a bacterium.Free PMC Article

Similar articles
 

Select item 121424244.

Simultaneous coexpression of Borrelia burgdorferi Erp proteins occurs through a specific, erp locus-directed regulatory mechanism.

El-Hage N, Stevenson B.

J Bacteriol. 2002 Aug;184(16):4536-43.

An individual Borrelia burgdorferi bacterium can encode as many as 13 different Erp (OspE/F-related) proteins from mono-and bicistronic loci that are carried on up to 10 separate plasmids. We demonstrate through multilabel immunofluorescence analyses that individual bacteria simultaneously coexpress their entire Erp protein repertoire. While it has been proposed that B. burgdorferi controls expression of Erp and other plasmid-encoded proteins through changes in DNA topology, we observed regulated Erp expression in the absence of detectable differences in DNA supercoiling. Likewise, inhibition of DNA gyrase had no detectable effect on Erp expression. Furthermore, expression of loci physically adjacent to erp loci was observed to be independently regulated. It is concluded that Erp expression is regulated by a mechanism(s) directed at erp loci and not by a global, plasmid-wide mechanism.Free PMC Article

Similar articles

Select item 107622445.

Efficient targeted mutagenesis in Borrelia burgdorferi.

Bono JL, Elias AF, Kupko JJ 3rd, Stevenson B, Tilly K, Rosa P.

J Bacteriol. 2000 May;182(9):2445-52.

Genetic studies in Borrelia burgdorferi have been hindered by the lack of a nonborrelial selectable marker. Currently, the only selectable marker is gyrB(r), a mutated form of the chromosomal gyrB gene that encodes the B subunit of DNA gyrase and confers resistance to the antibiotic coumermycin A(1). The utility of the coumermycin-resistant gyrB(r) gene for targeted gene disruption is limited by a high frequency of recombination with the endogenous gyrB gene. A kanamycin resistance gene (kan) was introduced into B. burgdorferi, and its use as a selectable marker was explored in an effort to improve the genetic manipulation of this pathogen. B. burgdorferi transformants with the kan gene expressed from its native promoter were susceptible to kanamycin. In striking contrast, transformants with the kan gene expressed from either the B. burgdorferi flaB or flgB promoter were resistant to high levels of kanamycin. The kanamycin resistance marker allows efficient direct selection of mutants in B. burgdorferi and hence is a significant improvement in the ability to construct isogenic mutant strains in this pathogen.Free PMC Article

Similar articles
 https://en.wikipedia.org/wiki/Kanamycin_A
 

Select item 107150166.

Disruption of the Borrelia burgdorferi gac gene, encoding the naturally synthesized GyrA C-terminal domain.

Knight SW, Kimmel BJ, Eggers CH, Samuels DS.

J Bacteriol. 2000 Apr;182(7):2048-51.

The C-terminal domain of the A subunit of DNA gyrase, which we term Gac, is naturally synthesized in Borrelia burgdorferi as an abundant DNA-binding protein. Full-length GyrA, which includes the C-terminal domain, is also synthesized by the spirochete and functions as a subunit of DNA gyrase. We have disrupted synthesis of Gac as an independent protein and demonstrated that it is not essential for growth in a coumarin-resistant background. We detected no alterations in DNA maintenance, condensation, or topology in B. burgdorferi lacking this small DNA-binding protein.

Free PMC Article

Similar articles
 

Select item 111195607.

Homologous and heterologous Borrelia burgdorferi challenge of infection-derived immune rabbits using host-adapted organisms.

Shang ES, Wu XY, Lovett MA, Miller JN, Blanco DR.

Infect Immun. 2001 Jan;69(1):593-8.

We have recently found that strain B31 infection-immune rabbits are completely protected against homologous challenge with large numbers (>10(6)) of host-adapted Borrelia burgdorferi (HAB) (E. S. Shang, C. I. Champion, X. Wu, J. T. Skare, D. B. Blanco, J. N. Miller, and M. A. Lovett, Infect. Immun. 68:4189-4199, 2000). In this study, we have extended these findings to determine whether B31 strain infection-immune rabbits are also protected against heterologous HAB challenge. Infection-immune rabbits challenged with large numbers (>10(6)) of homologous HAB strain B31 were completely protected from erythema migrans (EM) and skin and disseminated infection. In contrast, infection-immune rabbits challenged with heterologous HAB strains N40 and Sh-2-82 were completely susceptible to EM and skin and disseminated infection; challenge with strain 297 also resulted in EM and infection of the skin and viscera, but clearance of infection occurred 3 weeks postchallenge. These findings confirm that immunity elicited in rabbits by B31 strain infection confers complete protection against large-dose homologous HAB challenge but not against a heterologous strain.Free PMC Article

Similar articles

Select item 104696658.

Natural synthesis of a DNA-binding protein from the C-terminal domain of DNA gyrase A in Borrelia burgdorferi.

Knight SW, Samuels DS.

EMBO J. 1999 Sep 1;18(17):4875-81.

We have identified a 34 kDa DNA-binding protein with an HU-like activity in the Lyme disease spirochete Borrelia burgdorferi. The 34 kDa protein is translated from an abundant transcript initiated within the gene encoding the A subunit of DNA gyrase. Translation of the 34 kDa protein starts at residue 499 of GyrA and proceeds in the same reading frame as full-length GyrA, resulting in an N-terminal-truncated protein. The 34 kDa GyrA C-terminal domain, although not homologous, substitutes for HU in the formation of the Type 1 complex in Mu transposition, and complements an HU-deficient strain of Escherichia coli. This is the first example of constitutive expression of two gene products in the same open reading frame from a single gene in a prokaryotic cellular system.Free PMC Article

Similar articles
 

Select item 97972249.

Mutations in Bartonella bacilliformis gyrB confer resistance to coumermycin A1.

Battisti JM, Smitherman LS, Samuels DS, Minnick MF.

Antimicrob Agents Chemother. 1998 Nov;42(11):2906-13.

This study describes the first isolation and characterization of spontaneous mutants conferring natural resistance to an antibiotic for any Bartonella species. The Bartonella bacilliformis gyrB gene, which encodes the B subunit of DNA gyrase, was cloned and sequenced. The gyrB open reading frame (ORF) is 2,079 bp and encodes a deduced amino acid sequence of 692 residues, corresponding to a predicted protein of approximately 77.5 kDa. Sequence alignment indicates that B. bacilliformis GyrB is most similar to the GyrB protein from Bacillus subtilis (40.1% amino acid sequence identity) and that it contains the longest N-terminal tail (52 residues) of any GyrB characterized to date. The cloned B. bacilliformis gyrB was expressed in an Escherichia coli S30 cell extract and was able to functionally complement a temperature-sensitive E. coli Cour gyrB mutant (strain N4177). We isolated and characterized spontaneous mutants of B. bacilliformis resistant to coumermycin A1, an antibiotic that targets GyrB. Sequence analysis of gyrB from 12 Cour mutants of B. bacilliformis identified single nucleotide transitions at three separate loci in the ORF. The predicted amino acid substitutions resulting from these transitions are Gly to Ser at position 124 (Gly124-->Ser), Arg184-->Gln, and Thr214-->Ala or Thr214-->Ile, which are analogous to mutated residues found in previously characterized resistant gyrB genes from Borrelia burgdorferi, E. coli, Staphylococcus aureus, and Haloferax sp. The Cour mutants are three to five times more resistant to coumermycin A1 than the wild-type parental strainFree PMC Article

Similar articles
 

Select item 904312710.

Oligonucleotide-mediated genetic transformation of Borrelia burgdorferi.

Samuels DS, Garon CF.

Microbiology. 1997 Feb;143 ( Pt 2):519-22.

We have used short oligonucleotides to genetically transform the Lyme disease spirochaete Borrelia burgdorferi. The oligonucleotides are derived from the sequence of an Arg-133 to Ile mutant gyrB (chromosomal) gene that confers resistance to the antibiotic coumermycin A1. Oligonucleotides were about 10,000-fold less efficient at transformation, on a molar basis, than longer PCR-generated substrates. All of the transformants tested contained the predicted site-directed silent mutation in their gyrB genes. Antisense oligonucleotides were more efficient at transformation than either sense or double-stranded oligonucleotides. This is the first demonstration of oligonucleotides used to introduce site-directed mutations directly into the genome of a bacterium.

Similar articles
 

Select item 883069111.

Directed insertion of a selectable marker into a circular plasmid of Borrelia burgdorferi.

Rosa P, Samuels DS, Hogan D, Stevenson B, Casjens S, Tilly K.

J Bacteriol. 1996 Oct;178(20):5946-53.

Studies of the biology of Borrelia burgdorferi and the pathogenesis of Lyme disease are severely limited by the current lack of genetic tools. As an initial step toward facile genetic manipulation of this pathogenic spirochete, we have investigated gene inactivation by allelic exchange using a mutated borrelial gyrB gene that confers resistance to the antibiotic coumermycin A1 as a selectable marker. We have transformed B. burgdorferi by electroporation with a linear fragment of DNA in which this selectable marker was flanked by sequences from a native borrelial 26-kb circular plasmid. We have identified coumermycin A1-resistant transformants in which gyrB had interrupted the targeted site on the 26-kb plasmid via homologous recombination with the flanking sequences. Antibiotic resistance conferred by the mutated gyrB gene on the plasmid is dominant, and transformed spirochetes carrying this plasmid do not contain any unaltered copies of the plasmid. Coumermycin A1 resistance can be transferred to naive B. burgdorferi by transformation with borrelial plasmid DNA from the initial transformants. This work represents the first example of a directed mutation in B. burgdorferi whereby a large segment of heterologous DNA (gyrB) has been inserted via homologous recombination with flanking sequences, thus demonstrating the feasibility of specific gene inactivation by allelic exchange.Free PMC Article

Similar articles
 

Select item 792896512.

Genetic transformation of the Lyme disease agent Borrelia burgdorferi with coumarin-resistant gyrB.

Samuels DS, Mach KE, Garon CF.

J Bacteriol. 1994 Oct;176(19):6045-9.

No useful method to genetically manipulate Borrelia burgdorferi, the causative agent of Lyme disease, has been developed previously. We have used resistance to the coumarin antibiotic coumermycin A1, an inhibitor of DNA gyrase, as a genetic marker to monitor the transformation of B. burgdorferi by electroporation. Introduction of site-directed mutations into the gyrB gene demonstrated that transformation was successful, provided evidence that homologous recombination occurs on the chromosome, and established that mutations at Arg-133 of DNA gyrase B confer coumermycin A1 resistance in B. burgdorferi. The coumermycin A1-resistant gyrB marker and genetic transformation can now be applied toward dissecting the physiology and pathogenesis of the Lyme disease agent on a molecular genetic levelFree PMC Article

Similar articles
 

Select item 818860913.

gyrB mutations in coumermycin A1-resistant Borrelia burgdorferi.

Samuels DS, Marconi RT, Huang WM, Garon CF.

J Bacteriol. 1994 May;176(10):3072-5.

We have isolated and characterized mutants of Borrelia burgdorferi that are resistant to the antibiotic coumermycin A1, which targets the B subunit of DNA gyrase. Mutants had either 100- or 300-fold higher resistance to coumermycin A1 than wild-type B. burgdorferi. In each case, a single point mutation in the gyrB gene converted Arg-133 to Gly or Ile. Mutations in the homologous Arg residue of Escherichia coli DNA gyrase are also associated with resistance to coumarin antimicrobial agents.Free PMC Article

Similar articles
 

Select item 838163914.

Coumermycin A1 inhibits growth and induces relaxation of supercoiled plasmids in Borrelia burgdorferi, the Lyme disease agent.

Samuels DS, Garon CF.

Antimicrob Agents Chemother. 1993 Jan;37(1):46-50.

Coumermycin A1 is an inhibitor of DNA gyrase, an enzyme that catalyzes supercoiling of DNA and is required for bacterial DNA replication. We have investigated the activity of this coumarin antibiotic on Borrelia burgdorferi, a spirochete and the causative agent of Lyme disease. B. burgdorferi was more susceptible than many other eubacteria to coumermycin as well as novobiocin, another coumarin antibiotic; this contrasted with its relative resistance to the DNA gyrase inhibitors nalidixic acid, oxolinic acid, and ciprofloxacin. Coumermycin at 0.2 micrograms/ml inhibited the growth of B. burgdorferi B31 in BSK II medium. A 100-fold-lower concentration induced the relaxation of two negatively supercoiled circular plasmids within 2 h. Plasmid supercoiling was restored within 2 h of removal of coumermycin. These results suggest that B. burgdorferi has a DNA gyrase and that this enzyme's activity is required for growth. Furthermore, structural analogs of coumermycin may be considered as treatments for Lyme disease.Free PMC Article

Similar articles

 https://en.wikipedia.org/wiki/Coumermycin_A1

 

Select item 164475015.

Linear- and circular-plasmid copy numbers in Borrelia burgdorferi.

Hinnebusch J, Barbour AG.

J Bacteriol. 1992 Aug;174(16):5251-7.

Borrelia burgdorferi, the Lyme disease agent, and other members of the spirochetal genus Borrelia have double-stranded linear plasmids in addition to supercoiled circular plasmids. The copy number relative to the chromosome was determined for 49- and 16-kb linear plasmids and a 27-kb circular plasmid of the type strain, B31, of B. burgdorferi.

 All three plasmids were present in low copy number, about one per chromosome equivalent, as determined by relative hybridizations of replicon-specific DNA probes. The low copy number of Borrelia plasmids suggests that initiation of DNA replication and partitioning are carefully controlled during the cell division cycle. The copy numbers of these three plasmids of strain B31 were unchanged after approximately 7,000 generations in continuous in vitro culture. A clone of B. burgdorferi B31 that did not contain the 16-kb linear plasmid was obtained after exposure of a culture to novobiocin, a DNA gyrase inhibitor. The plasmid-cured strain contains only one linear plasmid, the 49-kb plasmid, and thus has the smallest genome reported to date for B. burgdorferi.Free PMC Article

Similar articles

Back to top