Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When the nonprotein chromophore of neocarzinostatin was allowed to react with either calf thymus DNA or poly(dA-dT) . poly(dA-dT) in the presence of 2-mercaptoethanol and the DNA was precipitated with ethanol, 5% of the fluorescence attributable to the naphthalene rings of the chromophore coprecipitated with the DNA. Most of this fluorescence remained attached to DNA through successive reprecipitations, suggesting formation of covalent adducts between chromophore and DNA. Enzymatically digested poly(dA-dT) . poly(dA-dT)-chromophore adduct contained, in addition to deoxyadenosine and thymidine, several highly fluorescent hydrophobic products, separable by reverse-phase chromatography, all of which contained both adenine and thymine radiolabel, as well as chromophore radiolabel. One such product consistently had twice as much thymine as adenine, suggesting a structure chromophore-d(TpApT), in which the attached chromophore rendered both phosphodiester bonds refractory to endonuclease S1. This adduct fragment was completely hydrolyzed at pH 12, releasing adenine, 3'-dTMP, and 5'-dTMP. At pH 7, the adduct fragment slowly released chromophore and 3'-dTMP with parallel kinetics, leaving a modified d(ApT), which was cleaved by snake venom phosphodiesterase to yield 5'-dTMP and a modified deoxyadenosine. These hydrolysis patterns are unlike those of any previously characterized base or phosphotriester DNA adduct but rather indicate an altered deoxyadenosine sugar. The formation of adducts containing a modified deoxyribose suggests that deoxyribose may be the site of covalent chromophore attachment. Alteration of this same site, possibly the 5'-carbon of the sugar moiety, may account for the extreme lability of the phosphodiester bond.
 ...
PMID:Covalent adducts of DNA and the nonprotein chromophore of neocarzinostatin contain a modified deoxyribose. 621 Sep 7

A systematic survey for the presence of plasmids in 17 different xenobiotic-degrading Sphingomonas strains was performed. In almost all analyzed strains, two to five plasmids with sizes of about 50 to 500 kb were detected by using pulsed-field gel electrophoresis. A comparison of plasmid preparations untreated or treated with S1 nuclease suggested that, in general, Sphingomonas plasmids are circular. Hybridization experiments with labeled gene probes suggested that large plasmids are involved in the degradation of dibenzo-p-dioxin, dibenzofuran, and naphthalenesulfonates in S. wittichii RW1, Sphingomonas sp. HH69, and S. xenophaga BN6, respectively. The plasmids which are responsible for the degradation of naphthalene, biphenyl, and toluene by S. aromaticivorans F199 (pNL1) and of naphthalenesulfonates by S. xenophaga BN6 (pBN6) were site-specifically labeled with a kanamycin resistance cassette. The conjugative transfer of these labeled plasmids was attempted with various bacterial strains as putative recipient strains. Thus, a conjugative transfer of plasmid pBN6 from S. xenophaga BN6 to a cured mutant of strain BN6 and to Sphingomonas sp. SS3 was observed. The conjugation experiments with plasmid pNL1 suggested a broader host range of this plasmid, because it was transferred without any obvious structural changes to S. yanoikuyae B1, Sphingomonas sp. SS3, and S. herbicidovorans. In contrast, major plasmid rearrangements were observed in the transconjugants after the transfer of plasmid pNL1 to Sphingomonas sp. HH69 and of pBN6 to Sphingomonas sp. SS3. No indications for the transfer of a Sphingomonas plasmid to bacteria outside of the Sphingomonadaceae were obtained.
 ...
PMID:Detection and characterization of conjugative degradative plasmids in xenobiotic-degrading Sphingomonas strains. 1517