Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have demonstrated recombination of bacteriophage T7 DNA in vitro. An extract of Escherichia coli B cells infected with wild-type T7(T7+) is incubated with mature DNA extracted from T7 phage. Packaging of the exogenous DNA within the phage head appears to be preceded by recombination of exogenously added DNA with DNA present in the extracts. In order to detect the recombination, we used an exogenous DNA bearing a marker (ss-) such that progeny phage which have packaged this marker are able to plate on Shigella sonnei D2 571-48, whereas T7+ phage present in the extracts do not. The recombinational process bears many of the characteristics of in vivo recombination. The exogenous DNA is not packaged intact but undergoes fragmentation to a length of about 3000 base pairs before being incorporated into a mature DNA molecule. If ss- DNA bearing an amber mutation is used in the assay, the frequency of amber+ progeny produced varies with the distance of the amber marker from the ss- marker. When DNA bearing three mutations is used in the reaction, phage heterozygous for the unselected marker are readily detected. Finally the products of phage genes 4 (DNA replication protein), 5(DNA polymerase), and 6(exonuclease), genes previously implicated in recombination in vivo, are required for the in vitro reaction.
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PMID:Genetic recombination of bacteriophage T7 DNA in vitro. 106 79

A multicopy plasmid, 2.1 kb in size, was isolated from Shigella sonnei and named pKYM. This plasmid is cryptic and isolated along with pKY-1, a ColE1-like plasmid. In this paper, we report the physical map of pKYM and some characters required for its multiplication. The replication of the plasmid DNA does not require DNA polymerase I but depends on protein(s) produced by itself. The plasmid is poorly mobilized by the F factor.
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PMID:Characterization of a mini plasmid isolated from Shigella sonnei. 609 86

pNZ500 is a 1.5 kb cryptic plasmid from a Shigella sonnei isolate. It was introduced into Escherichia coli by cotransformation, where it is maintained at about 30 copies per chromosome equivalent. Hybridization studies show that pNZ500 exhibits a high level of sequence similarity to other 1.5 kb plasmids found in different S. sonnei isolates but shares no homology with larger S. sonnei plasmids. pNZ500 shares a small degree of sequence homology with pBR322 and with pAC184. The homology with pBR322 is restricted to sequences close to the ori-bom region of this plasmid. Nevertheless, pNZ500 maintenance in E. coli is not dependent on DNA polymerase I activity, and does depend on continuing protein synthesis. pNZ500 encodes two polypeptide gene products whose monomer molecular weights are 24500 and 18000. The examination of host cells for the expression of possible plasmid phenotypes revealed no differences between cells bearing pNZ500 and plasmidless cells.
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PMID:A cryptic plasmid from Shigella sonnei. 631 45

Mutants of Shigella sonnei (S. sonnei) deficient in DNA polymerase I were isolated after mutagenesis with nitrosoguanidine. The isolation of the mutants was facilitated by the use of a strain harboring plasmid pBR313 which required DNA polymerase I for its muliplication. The mutants isolated could not maintain the plasmid and became sensitive to methyl methanesulfonate (MMS) and to ultraviolet light (UV) irradiation. Assays performed on crude extracts established that the mutants were deficient in an enzyme with DNA polymerase activity. All of these properties are the same as those of E. coli polA. Several MMS-resistant revertants isolated from one of the S. sonnei polA mutants regained 3-120% of the DNA polymerase activity found in the extracts of the wild-type parent strain. Most though not all of the revertants could support the multiplication of plasmid pBR313.
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PMID:Mutants of Shigella sonnei deficient in DNA polymerase I. 702 49