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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We purified fission yeast DNA topoisomerase II (topo II) to apparent homogeneity. It consists of a single 165-kDa polypeptide in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and, upon treatment with a bifunctional reagent, doubles its molecular weight. Limited proteolysis of intact topo II by papain produces a 125-kDa core, which lacks the N-terminal 75 and the C-terminal approximately 260 amino acids but still contains regions similar to those of bacterial or phage T4 topo II subunits. The core retains relaxing and unknotting activities. Further digestion inactivates the core, cleaving it at the middle of the GyrB-like domain and at the beginning of the GyrA-like domain. Therefore, papain appears to cleave spatially distinct subdomains of topo II. We made top2 mutant genes deleted of the C-terminal 286 or N-terminal 74 amino acids, which can substitute for the wild-type top2+ gene in mitosis and meiosis. However, a mutant containing deletions of both termini cannot rescue the top2 null mutant, despite the fact that the product is enzymatically active. Therefore, the top2 product of the doubly truncated gene may not fulfill all of the in vivo requirements for top2+ function.
Mol Cell Biol 1991 Dec
PMID:A functional 125-kDa core polypeptide of fission yeast DNA topoisomerase II. 165 25

To examine the mechanism of recombination involved in the formation of specialized transducing phage during the induction of bacteriophage lambda, we have determined the nucleotide sequences of the recombination junctions of lambda bio phages. The results indicate that abnormal excision takes place at many sites on both bacterial and phage genomes and that the recombination sites have short regions of homology (5-14 bp). Some of the sequences of the recombination sites were similar to the consensus sequences of DNA gyrase-cleavage sites and repetitive extragenic palindromic (REP) sequences. These results showed that abnormal excision is a type of illegitimate recombination. The possible involvement of DNA gyrase in this recombination is discussed.
Mol Gen Genet 1991 Nov
PMID:Molecular analysis of the recombination junctions of lambda bio transducing phages. 166 May 69

The location of oxolinis acid-induced gyrase cleavage sites on pBR322 and pUB110 plasmid DNA in Bacillus subtilis cells has been studied and established. The treated Bacillus subtilis protoplasts were used in the study. Coordinates of the gyrase cleavage sites were compared to the location of the illegitimate recombination sites precisely mapped on the plasmid genomes. The obtained data indicate involvement of the DNA gyrase in formation of a fraction of recombinants in Bacillus subtilis.
Mol Gen Mikrobiol Virusol 1991 Aug
PMID:[The role of DNA-gyrase from Bacillus subtilis during intermolecular irregular recombination]. 166 91

Previous work in our laboratory suggested that DNA topology could be implicated in the regulation of the division gene ftsZ. To settle this question, we have selected and characterized mutants in the gyrB gene able to phenotypically suppress the defects of the ftsZ84 mutation. No strict correlation was found between the degree of plasmid DNA relaxation and the level of suppression of the thermosensitivity of the ftsZ84 strain. Interestingly, the class of mutants that shows maximal suppression is substantially unaffected in DNA topology. In addition, the amount of ftsZ-specific mRNA in this class of mutants is comparable to that present in the ftsZ84 strain. These results hint that the ability of these gyrB mutants to correct the effects of the ftsZ84 mutation is largely unrelated to the function of the GyrB (as a part of DNA gyrase) in the control of DNA superhelicity and suggest hitherto unsuspected interaction between the ftsZ and gyrB gene products.
Mol Microbiol 1991 May
PMID:A class of gyrB mutants, substantially unaffected in DNA topology, suppresses the Escherichia coli K12 ftsZ84 mutation. 172 Jan 86

The data presented confirm the possibility of enzymatic formation of discrete DNA-fragments appearing during fractionation of nuclear DNA by FIGE. Teniposide-dependent pattern of DNA-fragments as well as occurrence of protein-linked DNA breaks suggest that discrete cleavage of intact nuclear DNA is modulated by DNA topoisomerase II. The possible relationship between discrete DNA-fragments and the higher order chromatin folding are discussed.
Mol Biol (Mosk)
PMID:[Fractionation of eukaryotic DNA in a pulsed electrical field. II. Discrete DNA fragments and level of structural organization of chromatin]. 181 95

The 43 kDa N-terminal ATPase domain of the Escherichia coli DNA gyrase B protein has been purified from an over-expressing strain. This protein has been crystallized in two crystal forms, both in the presence of the non-hydrolysable ATP analogue 5'-adenylyl-beta,gamma-imidodiphosphate. The first crystal form is monoclinic P2(1), with cell dimensions a = 76 A, b = 88 A, c = 82 A, beta = 105.5 degrees, and diffracts to at least 2.7 A resolution using synchrotron radiation. Crystal density measurements suggest that there are two molecules in the asymmetric unit (Vm = 3.08 A3/Da). The second crystal form is orthorhombic C222(1), with cell dimensions a = 89.2 A, b = 143.1 A and c = 79.8 A. The crystals diffract to beyond 3 A and are stable for at least 100 hours when exposed to X-rays from a rotating anode source. The asymmetric unit of this crystal form appears to contain one molecule (Vm = 2.96 A3/Da). Data have already been collected to 5 A resolution from native crystals of this second form, and to 6 A resolution from three heavy-atom derivatives. Electron density maps calculated using phases obtained from these derivatives show features consistent with secondary structural elements, and have allowed the molecular boundary to be determined. Higher resolution native and derivative data are being collected.
J Mol Biol 1991 Jan 05
PMID:Preliminary crystallographic analysis of the ATP-hydrolysing domain of the Escherichia coli DNA gyrase B protein. 184 27

The administration of the DNA topoisomerase II inhibitors 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) (10(-7) M), VP-16 (2 x 10(-7) M), or novobiocin (1.5 x 10(-4) M) reduces the growth activity of human promonocytic leukemia U-937 cells, by arresting them preferentially at the G2 (m-AMSA and VP-16) or at the G1 and G2 (novobiocin) phases of the cell cycle. Under these conditions, m-AMSA and VP-16 induce the differentiation of the cells efficiently, as proved both by an increase in the production of reactive oxygen species and by the activation of the surface expression of CD11b and CD11c, two differentiation-specific antigens. Novobiocin also induces the expression of those differentiation markers, but to a lesser extent. Analyses by Northern blot indicate that the topoisomerase II inhibitors reduce the levels of c-myc and beta-actin mRNA and increase the levels of vimentin mRNA. The expression of vimentin is also stimulated at the protein level, as indicated by immunofluorescence assays. This represents one of the few known instances in which topoisomerase inhibitors stimulate gene expression in eukaryotic cells.
Mol Pharmacol 1991 Apr
PMID:Differentiation of human promonocytic leukemia U-937 cells with DNA topoisomerase II inhibitors: induction of vimentin gene expression. 185 89

Many promoters are sensitive to DNA supercoiling, and it is becoming apparent that this may play an important role in gene regulation. The twin supercoiled-domain hypothesis (Liu and Wang, 1987) proposes that transcription can lead to local variation in supercoiling. The mutant leu-500 promoter has presented a long-standing problem to the understanding of the control of promoter function by DNA supercoiling. This promoter is activated by mutations in the gene encoding topoisomerase I, but is apparently unaffected by mutations in the genes encoding DNA gyrase. We propose a model to explain the anomalous regulation of this promoter, based on the twin supercoiled-domain model. This allows us to account for the unusual properties of the leu-500 promoter, and confirms the biological importance of the twin supercoiled-domain model. We suggest that such topological coupling between promoters may be general, leading to co-operativity and anti-co-operativity between divergent promoter pairs.
Mol Microbiol 1991 Apr
PMID:Local DNA topology and gene expression: the case of the leu-500 promoter. 185 4

Using a variety of mutagenic methods, we have generated a series of ciprofloxacin-resistant mutants derived from Escherichia coli strains which overproduce the DNA gyrase A protein. Many of these mutants are found to overexpress a 60 kD protein which is shown to be highly homologous in terms of N-terminal amino acid sequence to the E. coli heat-shock protein, GroEL. Other evidence confirms that the 60 kD protein is unrelated to DNA gyrase and is similar, but not identical, to GroEL.
Mol Microbiol 1990 Mar
PMID:Escherichia coli cells resistant to the DNA gyrase inhibitor, ciprofloxacin, overproduce a 60 kD protein homologous to GroEL. 197 34

The mechanism of anaerobic regulation of synthesis of colicins E1, E2, E3, K and D was studied. It was found that anaerobiosis significantly increases expression of the genes for colicins E1, E2, E3, K, and D. Experiments with novobiocin (a DNA gyrase inhibitor) showed that colicin synthesis in minicells and derepressed colicin synthesis in cells are dramatically reduced by relaxation of DNA supercoiling. A good correlation was observed between the levels of colicin synthesis and plasmid DNA supercoiling and the degree of aeration of the cultures. Thus, the regulation of colicin gene expression in response to a change in aeration appears to be mediated by environmentally induced variations in DNA supercoiling.
Mol Gen Genet 1991 Feb
PMID:A physiological role for DNA supercoiling in the anaerobic regulation of colicin gene expression. 200 75


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