title: A complex family of class-II restriction endonucleases, DsaI-VI, in Dactylococcopsis salina.
abstract: A series of class-II restriction endonucleases (ENases) was discovered in the halophilic, phototrophic, gas-vacuolated cyanobacterium Dactylococcopsis salina sp. nov. The six novel enzymes are characterized by the following recognition sequences and cut positions: 5'-C decreases CRYGG-3' (DsaI); 5'-GG decreases CC-3' (DsaII); 5'-R decreases GATCY-3' (DsaIII); 5'-G decreases GWCC-3' (DsaIV); 5'-decreases CCNGG-3' (DsaV); and 5'-GTMKAC-3' (DsaVI), where W = A or T, M = A or C, K = G or T, and N = A, G, C or T. In addition, traces of further possible activity were detected. DsaI has a novel sequence specificity and DsaV is an isoschizomer of ScrFI, but with a novel cut specificity. A purification procedure was established to separate all six ENases, resulting in their isolation free of contaminating nuclease activities. DsaI cleavage is influenced by N6-methyladenine residues [derived from the Escherichia coli-encoded DNA methyltransferase (MTase) M.Eco damI] within the overlapping sequence, 5'-CCRYMGGATC-3'; DsaV hydrolysis is inhibited by a C-5-methylcytosine residue in its recognition sequence (5'-CMCNGG-3'), generated in some DsaV sites by the E. coli-encoded MTase, M.Eco dcmI.
authors.affiliation: Biochemical Research Center, Boehringer Mannheim GmbH, Penzberg, F.R.G.
authors.forename: F
authors.initials: F
authors.lastname: Laue
authors.forename: L R
authors.initials: LR
authors.lastname: Evans
authors.forename: M
authors.initials: M
authors.lastname: Jarsch
authors.forename: N L
authors.initials: NL
authors.lastname: Brown
authors.forename: C
authors.initials: C
authors.lastname: Kessler
mesh_terms: D001483:Base Sequence; D002021:Buffers; D002845:Chromatography; D000458:Cyanobacteria / Q000201:enzymology*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism*; D008745:Methylation; D008969:Molecular Sequence Data; D013379:Substrate Specificity
chemical_list: D002021:Buffers; C056536:endodeoxyribonuclease BstYI; C067486:endodeoxyribonuclease DsaI; C045297:CCNGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; C024403:GGCC-specific type II deoxyribonucleases; C038308:GGWCC-specific type II deoxyribonucleases; C067488:GTMKAC-specific type II deoxyribonucleases