Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study deals with the effects of a temperature-sensitive (ts) mutation at the gene encoding the DNA gyrase B subunit (gyrBts) and a deletion of the top gene encoding the omega protein upon the superhelical density of the pAO3 plasmid in E. coli cells. The alteration of the DNA gyrase B subunit is shown to lead to a partial relaxation of DNA. On the other hand, the lack of omega protein due to the top gene deletion leads to an abnormally high degree of DNA supercoiling. In a double gyrBts delta top mutant the DNA supercoiling is greater than native at the permissive temperature, while under nonpermissive conditions a partial relaxation is observed. However, the pattern of DNA relaxation in the latter case is quite different from that in a single gyrBts mutant. The conclusion is that the native supercoiling of DNA in the cell is maintained through the counter-activities of DNA gyrase and the omega protein.
Mol Gen Genet 1984
PMID:Native supercoiling of DNA: the effects of DNA gyrase and omega protein in E. coli. 609 79

Illegitimate recombination dependent on DNA gyrase in a cell-free system has previously been described. We have now mapped DNA gyrase cleavage sites in the vicinity of known recombination sites in pBR322. Among five recombination sites examined, three were found to coincide with a DNA gyrase cleavage site. This result suggests that the cleavage of DNA by DNA gyrase has a central role in the recombination process.
Mol Gen Genet 1984
PMID:Mechanism of illegitimate recombination: common sites for recombination and cleavage mediated by E. coli DNA gyrase. 609 84

A class of rpoB mutations is described which suppresses replication and transcription deficiency in gyrB-ts mutants shifted to a nonpermissive temperature. The compensatory effect of an altered subunit B of RNA polymerase (rpoB) for the gyrB defect, indicates that transcription is a primary target of the B subunit of DNA gyrase. One gyrB mutation (gyrB402-ts) shows deficiency in chromosome elongation at the nonpermissive temperature, both in vivo and in cells permeabilized with toluene. It is therefore concluded that the gyrB polypeptide functions at least dually in replication; first, at the level of transcription initiation and second, at the level of chain polymerization.
Mol Gen Genet 1983
PMID:The gyrB gene product functions in both initiation and chain polymerization of Escherichia coli chromosome replication: suppression of the initiation deficiency in gyrB-ts mutants by a class of rpoB mutations. 619 15

The nucleotide sequences involved in the illegitimate recombination of four recombinants between bacteriophage lambda DNA and pBR322 in E. coli (lambda TA6, lambda KA3, lambda TA1R, and lambda KA7) were determined. Each resulted from recombination between regions of homology of 10 to 13 base pairs. The presence of a recA+ allele was found to stimulate recombination between lambda DNA and pBR322 approximately 10-fold. Lambda TA6, lambda KA3, and lambda KA7 were isolated in the presence of a recA+ allele and therefore, may have been generated by the recA recombination system. However, lambda TA1R was isolated in a recA mutant, and was presumably generated by a different recombination system. The possibility that it was generated by DNA gyrase is discussed. Two recombination events were required to form lambda KA7, which may indicate that it also was generated by DNA gyrase.
Mol Gen Genet 1982
PMID:Nucleotide sequence analysis of in vivo recombinants between bacteriophage lambda DNA and pBR322. 621 53

It has been found that strains carrying mutations in the dnaA gene are unusually sensitive to COU, NAL or NOV, which are known to inhibit DNA gyrase activities. The delay in the initiation of chromosome replication after COU treatment has been observed in cells with chromosomes synchronized by amino acid starvation or by temperature shift-up (dnaA46). The unusual sensitivity of growth to COU of the initiation mutant runs parallel to a higher sensitivity to the drug of the initiation of chromosome replication. The double mutant, dnaA46, cou-110 has been isolated and mutation cou-110 conferring resistance of growth, initiation and elongation of chromosome replication to COU was mapped in the gene coding for the subunit of DNA gyrase. The reduced frequency of appearance of the mutants resistant to COU, NAL, or NOV in the initiation mutant suggests that some mutations in genes coding for DNA gyrase subunits cannot coexist with the dnaA46 mutation. The possible mechanisms of the requirement of DNA gyrase for dnaA-dependent initiation of E. coli chromosome are discussed.
Mol Gen Genet 1980 Jan
PMID:Requirement of DNA gyrase for the initiation of chromosome replication in Escherichia coli K-12. 624 41

The mechanism of activating action of ATP on the repair synthesis of DNA was studied in the chromatin isolated from rat liver (G0). It was shown that chromatin catalyzed the conversion dNTP leads to dNDP leads to dNMP leads to NdR. The principal mechanism of activating action of ATP is the maintenance of dNTP levels. The maintenance is carried out mainly by the inhibition of dNTP's phosphatases and in less extent by the means of reaction dNDP leads to dNTP. Besides that, ATP partially suppresses 3' leads to 5' exonuclease of chromatin which degrades the nascent DNA. The activating action of ATP is connected neither with phosphorylation of histones, nor with the activities of ATP-dependent endo- or exonucleases, DNA gyrase, polynucleotide ligase, or DNA unwinding protein.
Mol Biol (Mosk)
PMID:[Mechanism of activating action of ATP on repair synthesis of DNA in chromatin]. 625 23

The effects of oxolinic acid and novobiocin, two known inhibitors of DNA gyrase, on in vivo transcription in E. coli were investigated. The drugs inhibit the incorporation of 3H-uridine into RNA. It is shown that the effect is due to a direct influence of DNA gyrase on transcription, independent of interference with replication. By the use of rifampicin and hybridization experiments it was found that treatment with intermediate concentrations of DNA gyrase inhibitors reduces the rate of rRNA synthesis to a smaller extent than the rate of total RNA synthesis. By following the completion of growing rRNA chains we have also obtained evidence indicating that the average rate of rRNA chain growth is decreased in cells treated with inhibitors of DNA gyrase.
Mol Gen Genet 1980
PMID:Involvement of DNA gyrase in rRNA synthesis in vivo. 625 88

When a culture of the gyrB41-ts mutant is shifted to the nonpermissive temperature, DNA synthesis is arrested at the initiation phase of chromosome replication. After thermal inactivation of the gyrB gene product reinitiation occurs in the presence of chloramphenicol but not in the presence of rifampicin. This suggests that the B subunit of DNA gyrase may regulate synthesis of an "initiator RNA". An rpoB202 mutation has been isolated which suppresses both the DnaA-initiation phenotype and the inhibitory action of antibiotics which are known to result in relaxation of chromosomal DNA in vivo. We propose that DNA tertiary structure rather than DNA gyrase itself plays an essential regulatory function in the dnaA-dependent transcription which precedes the initiation of chromosome replication.
Mol Gen Genet 1981
PMID:Essential role of the gyrB gene product in the transcriptional event coupled to dnaA-dependent initiation of Escherichia coli chromosome replication. 627 73

To investigate the interaction of subunits A and B of DNA gyrase during DNA supercoiling, a Cour mutant of Escherichia coli was obtained and the effect of nalidixic acid on the supercoiling of DNA by wild-type and mutant enzymes was assayed. The enzyme of the Cour strain proved to be more sensitive to nalidixic acid than the wild-type DNA gyrase. Hence the mutation affecting the B subunit can also change the properties of the A subunit, which fact suggests that the two subunits of DNA gyrase are in contact during DNA supercoiling.
Mol Gen Genet 1982
PMID:Changed properties of the A subunit in DNA gyrase with a B subunit mutation. 629 Aug 48

Interaction of DNA gyrase A- and B-subunits during the process of DNA supercoiling was studied. For this purpose a E. coli Cour-1 mutant resistant to coumermycin and containing a mutation in the B-subunit of DNA gyrase was isolated and the influence of the DNA gyrase A-subunit specific inhibitor-nalidixic acid-on DNA supercoiling by wild-type and mutant enzymes was investigated. It turned out that the enzyme from the Cour-1 mutant strain was more sensitive to nalidixic acid than the DNA gyrase from the wild-type strain. Hence, the mutation affecting the B-subunit is capable to change A-subunit properties. That makes it possible to draw the conclusion about a close structural interaction of DNA gyrase subunits during DNA supercoiling.
Mol Biol (Mosk)
PMID:[Interactions of subunits of DNA gyrase]. 629


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