title: Restriction/modification in Streptococcus thermophilus: isolation and characterization of a type II restriction endonuclease Sth455I.
abstract: Streptococcus thermophilus strain CNRZ 455 produces a type II restriction endonuclease designated Sth455I. This enzyme was isolated from cell extracts by anionic and cationic exchange chromatography. This yielded an enzyme preparation free of non-specific nucleases. The optimal reaction conditions for Sth455I are: MgCl2, 30 mM; pH range, 8-9; incubation temperature, 37-42 degrees C; and a high NaCl concentration, 100-200 mM. The results of single- and double-digestion experiments indicates that Sth455I is an isoschizomer of BstNI and EcoRII showing different sensitivity to methylation. The enzyme exhibits restriction activity on the DNA of three bacteriophages of S. thermophilus and no activity on the phage lytic for strain CNRZ 455. The restriction/modification system associated with this strain is discussed.
authors.affiliation: Laboratory of Applied Biochemistry-INRA Associated Laboratory, Faculty of Sciences, University of Nancy I, Vandoeuvre-les-Nancy, France.
authors.forename: C
authors.initials: C
authors.lastname: Guimont
authors.forename: P
authors.initials: P
authors.lastname: Henry
authors.forename: G
authors.initials: G
authors.lastname: Linden
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D001483:Base Sequence; D015280:DNA Restriction-Modification Enzymes; D004279:DNA, Viral / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D013291:Streptococcus / Q000201:enzymology / Q000235:genetics*; D017108:Streptococcus Phages / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D015280:DNA Restriction-Modification Enzymes; D004279:DNA, Viral; C046545:CCWGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific