title: [Specificity of new restrictases and methylases. Unusual modification of cytosine at position 4].
abstract: Fourteen restriction endonucleases and 4 methylases were isolated and purified from 14 strains of Citrobacter freundii and Escherichia coli, which were isolated from natural sources. To determine the nucleotide sequence recognized by the endonucleases a comparison of DNA cleavage patterns, the evaluation of the cleavage frequency of some DNA with known recognition sequences and mapping was used. It was determined that Cfr101 is a new enzyme recognizing 5'PuCCGGPy. Other restriction enzymes isolated were isoschizomers of: Cfr5I, Cfr11I, Eco60I, Eco61I--EcoRII; Cfr4I, Cfr8I, Cfr13I--Sau96I; Cfr6I--PvuII, Cfr9I--SmaI, Eco26I--HgiJII; Eco32I--EcoRV; Eco52I--XmaIII; Eco56I--NaeI. Some of the enzymes in C. freundii and E. coli were found for the first time. The methylases MCfrI; MCfr6I, MCfr9I and MCfr10I recognize the same nucleotide sequence as specific endonucleases isolated from the same strain. DNA modification in vitro by MCfrI and MCfr10I yields 5-methylcytosine and 4-methylcytosine by MCfr6I and MCfr9I.
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D002848:Chromatography, DEAE-Cellulose; D002954:Citrobacter / Q000201:enzymology; D003001:Cloning, Molecular; D003596:Cytosine / Q000032:analysis*; D004262:DNA Restriction Enzymes / Q000032:analysis* / Q000302:isolation & purification; D004279:DNA, Viral / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli / Q000201:enzymology; D008745:Methylation; D008780:Methyltransferases / Q000032:analysis* / Q000302:isolation & purification; D013379:Substrate Specificity
chemical_list: D004279:DNA, Viral; D003596:Cytosine; D008780:Methyltransferases; D004262:DNA Restriction Enzymes
vernacular_title: Izuchenie spetsifichnosti novykh restriktaz i metilaz. Neobychnaia modifikatsiia tsitozina po 4-mu polozheniiu.