Increase in synthesis and stability of

Mizushima, Takeshi; Ohtsuka, Y.; Mori, Hiroki; Miki, Toshiharu; Sekimizu, K.

doi:10.1007/s004380050325

Cited by 3 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1, lanes 1 and 2), as seen in the untreated cells (12). We suggested that the DNA relaxation after heat shock is not the result of a heat shock response, since the reaction was observed in an rpoH amber mutant where the heat shock response does not occur (10). As protein synthesis was blocked by chloramphenicol, under the present conditions, the present result confirms our previous conclusion.…”

Section: Requirement Of Newly Synthesized Protein For Dna Relaxation supporting

confidence: 82%

“…6). These results provide biochemical evidence suggesting that DNA gyrase participates in the reaction which causes the observed immediate increase in the linking number of DNA in cells after heat shock (10). In other words, DNA gyrase senses the temperature shift and changes the linking number of DNA.…”

Section: Influence Of Temperature On Linking Number Of Dna After the mentioning

confidence: 48%

“…The relaxed DNA returns rapidly to the original state, even at high temperature, and is concomitant with transient induction of heat shock proteins (10,12). Conversely, in a temperature-sensitive gyrA mutant, the DNA relaxation caused by heat shock is continuous together with the constitutive expression of heat shock proteins (10). Moreover, plasmid DNA in cells relaxed in the presence of chemicals which induce heat shock proteins.…”

mentioning

confidence: 92%

“…Moreover, plasmid DNA in cells relaxed in the presence of chemicals which induce heat shock proteins. Since DNA supercoiling has a considerable effect on the initiation of transcription (13,14), we proposed that the DNA relaxation affects expression of various genes, under conditions of heat shock (10).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Heat Shock-induced DNA Relaxation in Vitro by DNA Gyrase of Escherichia coli in the Presence of ATP

Kataoka

Mizushima

Ogata

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

Genetic studies revealed that DNA gyrase seems to catalyze immediate and transient DNA relaxation after Escherichia coli cells are exposed to heat shock (Ogata, Y., Mizushima, T., Kataoka, K., Miki, T., and Sekimizu, K. (1994) Mol. Gen. Genet. 244, 451-455). We have now obtained biochemical evidence to support this hypothesis. DNA gyrase catalyzed an increase in the linking number of DNA and relaxation of negatively supercoiled DNA, under physiological concentrations of ATP. Analyses by gel filtration chromatography of each subunit revealed that DNA relaxation activity co-migrated with each subunit. The linking number of DNA increased as the temperature increased. Further, the reaction was inhibited by nalidixic acid or by oxolinic acid. Based on these results, we propose that DNA gyrase participates in a concerted reaction with DNA topoisomerases in the immediate relaxation of DNA in cells exposed to heat shock.Closed circular duplex DNAs in cells are a mixture of topoisomers with different linking numbers under dynamic equilibrium. In Escherichia coli cells, DNA gyrase (1) and DNA topoisomerase I (2) are major enzymes responsible for changing the linking number of DNA (3-6). As the former enzyme is essential for cell growth (7,8), it probably has an important function in controlling the linking number of DNA in cells (6, 9).We reported that plasmid DNA in exponentially growing E. coli cells relaxed immediately after heat shock (10 -12) and that this relaxation apparently correlates with the induction of heat shock proteins. The relaxed DNA returns rapidly to the original state, even at high temperature, and is concomitant with transient induction of heat shock proteins (10, 12). Conversely, in a temperature-sensitive gyrA mutant, the DNA relaxation caused by heat shock is continuous together with the constitutive expression of heat shock proteins (10). Moreover, plasmid DNA in cells relaxed in the presence of chemicals which induce heat shock proteins. Since DNA supercoiling has a considerable effect on the initiation of transcription (13, 14), we proposed that the DNA relaxation affects expression of various genes, under conditions of heat shock (10).We also reported that relaxation of DNA after heat shock in a topA deletion mutant was blocked by nalidixic acid or by oxolinic acid, while the reaction was not affected by these drugs in the wild-type strain (12). DNA relaxation after heat shock in cells carrying both the topA deletion and a nalidixic acid-resistant gyrA mutation (nalA26) was not inhibited by nalidixic acid (12). Thus, not only DNA topoisomerase I but also DNA gyrase seems to catalyze DNA relaxation after heat shock. The literature suggests that DNA topoisomers are under thermal equilibrium in the presence of ATP and DNA gyrase. There is, however, no report of direct evidence that DNA gyrase catalyzes DNA relaxation under physiological concentrations of ATP; the enzyme was found to catalyze the reaction of DNA relaxation only in the absence of ATP (15, 16).We analyzed reaction products of purifi...

show abstract

Section: Requirement Of Newly Synthesized Protein For Dna Relaxation supporting

confidence: 82%

Section: Influence Of Temperature On Linking Number Of Dna After the mentioning

confidence: 48%

mentioning

confidence: 92%

mentioning

confidence: 99%

See 2 more Smart Citations

Heat Shock-induced DNA Relaxation in Vitro by DNA Gyrase of Escherichia coli in the Presence of ATP

Kataoka

Mizushima

Ogata

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…This has been attributed to the following mechanism. Expression of LetD protein leads to synthesis of 32, which induces DnaK and GroEL proteins, thus inhibiting DNA gyrase activity (15,40). In contrast to LetD, GyrI is the first identified regulatory factor for DNA gyrase which directly inhibits the activity in vitro and is encoded on the chromosome of E. coli.…”

Section: Analysis Of Nh 2 -Terminal Amino Acid Sequence Of Gyri Protein-mentioning

confidence: 99%

Identification of DNA Gyrase Inhibitor (GyrI) inEscherichia coli

Nakanishi¹,

Oshida²,

Matsushita³

et al. 1998

Journal of Biological Chemistry

View full text Add to dashboard Cite

DNA gyrase is an essential enzyme in DNA replication in Escherichia coli. It mediates the introduction of negative supercoils near oriC, removal of positive supercoils ahead of the growing DNA fork, and separation of the two daughter duplexes. In the course of purifying DNA gyrase from E. coli KL16, we found an 18-kDa protein that inhibited the supercoiling activity of DNA gyrase, and we coined it DNA gyrase inhibitory protein (GyrI). Its NH 2 -terminal amino acid sequence of 16 residues was determined to be identical to that of a putative gene product (a polypeptide of 157 amino acids) encoded by yeeB (EMBL accession no. U00009) and sbmC (Baquero, M. R., Bouzon, M., Varea, J., and Moreno, F. (1995) Mol. Microbiol. 18, 301-311) of E. coli. Assuming the identity of the gene (gyrI) encoding GyrI with the previously reported genes yeeB and sbmC, we cloned the gene after amplification by polymerase chain reaction and purified the 18-kDa protein from an E. coli strain overexpressing it. The purified 18-kDa protein was confirmed to inhibit the supercoiling activity of DNA gyrase in vitro. In vivo, both overexpression and antisense expression of the gyrI gene induced filamentous growth of cells and suppressed cell proliferation. GyrI protein is the first identified chromosomally nucleoid-encoded regulatory factor of DNA gyrase in E. coli.DNA gyrase, a type II topoisomerase in Escherichia coli, has the ability to cut a double-stranded DNA, pass an uncut portion of the duplex between the cut ends, and reseal the cut. It can introduce negative supercoils into covalently closed circular DNA and cause catenation and decatenation of two different DNA duplexes, in vitro (1). It has been established that the enzyme is essential for chromosomal replication in vivo (2). Moreover, there have been reports on the involvement of DNA gyrase in transcription from certain operons, DNA repair, and recombination in E. coli (2).DNA gyrase is composed of two subunits, A (GyrA) and B (GyrB), which are assembled in A 2 B 2 complexes, the active form (3-5). The active complex has been purified from E. coli (6) and reconstituted from the purified GyrA and GyrB (7-9). GyrA has an active center for the reactions of introducing and resealing the cuts of double-stranded DNA, whereas GyrB powers the reaction by catalyzing ATP hydrolysis.DNA gyrase is a target of two distinct classes of inhibitors, coumarins (10, 11) and quinolones (10, 12). Coumarins bind to GyrB and are competitive inhibitors with respect to ATP (11). In contrast, quinolones bind DNA gyrase when the enzyme is complexed with DNA and trap the enzyme in an abortive ternary complex, which, upon treatment with a denaturant, releases cleaved DNA with GyrA covalently attached to the 5Ј-phosphoryl ends generated at the cut site.There have been several reports on regulating DNA gyrase activity in E. coli. LetD (13) encoded on F factor inhibits DNA gyrase activity via the induction of synthesis of heat shock proteins (14). Another regulatory factor, cyclic AMP (cAMP) receptor (15), particip...

show abstract

Untitled

Adamčík¹,

Víglaský²,

Valle

et al. 2002

Electrophoresis

View full text Add to dashboard Cite

Changes in DNA supercoiling might be essential to generate the response of cellular machinery to temperature stress. The heat-induced structural transition for a topoisomer depends on the value of its specific linking difference. We detect only less negatively supercoiled DNA and an abundance of alternative irregular DNA forms at culture temperatures close to the growth limit of Escherichia coli. We show that the irregular forms are derived from regular plasmid DNAs and their population in the cells is temperature-dependent. Here, we show that it is possible to isolate and characterize individual DNA topoisomers directly from cells without a topoisomerase treatment. Temperature gradient gel electrophoresis (TGGE) and atomic force microscopy (AFM) were used to study the effect of bacteria growth temperature on the distribution of supercoiled DNA and its thermal stability.

show abstract

Increase in synthesis and stability of

Cited by 3 publications

References 0 publications

Heat Shock-induced DNA Relaxation in Vitro by DNA Gyrase of Escherichia coli in the Presence of ATP

Heat Shock-induced DNA Relaxation in Vitro by DNA Gyrase of Escherichia coli in the Presence of ATP

Identification of DNA Gyrase Inhibitor (GyrI) inEscherichia coli

Untitled

Contact Info

Product

Resources

About