scholarly journals The reactions of the EcoRi and other restriction endonucleases

1979 ◽  
Vol 179 (2) ◽  
pp. 353-365 ◽  
Author(s):  
S E Halford ◽  
N P Johnson ◽  
J Grinsted
Keyword(s):  
Restriction Endonuclease ◽  
Dna Sequences ◽  
Recognition Site ◽  
Single Strand ◽  
Restriction Endonucleases ◽  
Dna Duplex ◽  
Phosphodiester Bond ◽  
Linear Dna ◽  
Ecori Restriction ◽  
Dna Substrates

The reaction of the EcoRI restriction endonuclease was studied with both the plasmid pMB9 and DNA from bacteriophage lambda as the substrates. With both circular and linear DNA molecules, the only reaction catalysed by the EcoRI restriction endonuclease was the hydrolysis of the phosphodiester bond within one strand of the recognition site on the DNA duplex. The cleavage of both strands of the duplex was achieved only after two independent reactions, each involving a single-strand scission. The reactivity of the enzyme for single-strand scissions was the same for both the first and the second cleavage within its recognition site. No differences were observed between the mechanism of action on supercoiled and linear DNA substrates. Other restriction endonucleases were tested against plasmid pMB9. The HindIII restriction endonuclease cleaved DNA in the same manner as the EcoRI enzyme. However, in contrast with EcoRI, the Sa/I and the BamHI restriction endonucleases appeared to cleave both strands of the DNA duplex almost simultaneously. The function of symmetrical DNA sequences and the conformation of the DNA involved in these DNA–protein interactions are discussed in the light of these observations. The fact that the same reactions were observed on both supercoiled and linear DNA substrates implies that these interactions do not involve the unwinding of the duplex before catalysis.

scholarly journals The EcoRI restriction endonuclease with bacteriophage λ DNA. Equilibrium binding studies

1980 ◽  
Vol 191 (2) ◽  
pp. 593-604 ◽  
Author(s):  
S E Halford ◽  
N P Johnson
Keyword(s):  
Restriction Endonuclease ◽  
Dna Sequences ◽  
Reaction Rates ◽  
Recognition Site ◽  
Binding Studies ◽  
Dna Molecule ◽  
Recognition Sites ◽  
Equilibrium Binding ◽  
Ecori Restriction ◽  
Binding Curve

The EcoRI restriction endonuclease was found by the filter binding technique to form stable complexes, in the absence of Mg2+, with the DNA from derivatives of bacteriophage lambda that either contain or lack EcoRI recognition sites. The amount of complex formed at different enzyme concentrations followed a hyperbolic equilibrium-binding curve with DNA molecules containing EcoRI recognition sites, but a sigmoidal equilibrium-binding curve was obtained with a DNA molecule lacking EcoRI recognition sites. The EcoRI enzyme displayed the same affinity for individual recognition sites on lambda DNA, even under conditions where it cleaves these sites at different rates. The binding of the enzyme to a DNA molecule lacking EcoRI sites was decreased by Mg2+. These observations indicate that (a) the EcoRI restriction enzyme binds preferentially to its recognition site on DNA, and that different reaction rates at different recognition sites are due to the rate of breakdown of this complex; (b) the enzyme also binds to other DNA sequences, but that two molecules of enzyme, in a different protein conformation, are involved in the formation of the complex at non-specific consequences; (c) the different affinities of the enzyme for the recognition site and for other sequences on DNA, coupled with the different protein conformations, account for the specificity of this enzyme for the cleavage of DNA at this recognition site; (d) the decrease in the affinity of the enzyme for DNA, caused by Mg2+, liberates binding energy from the DNA-protein complex that can be used in the catalytic reaction.

scholarly journals The EcoRI restriction endonuclease with bacteriophage λ DNA. Kinetic studies

1980 ◽  
Vol 191 (2) ◽  
pp. 581-592 ◽  
Author(s):  
S E Halford ◽  
N P Johnson ◽  
J Grinsted
Keyword(s):  
Restriction Endonuclease ◽  
Protein Interactions ◽  
Dna Sequences ◽  
Individual Recognition ◽  
Kinetic Studies ◽  
Restriction Enzymes ◽  
Reaction Rates ◽  
Recognition Site ◽  
Experimental Conditions ◽  
Ecori Restriction

The kinetics of the reactions of the EcoRI restriction endonuclease at individual recognition sites on the DNA from bacteriophage lambda were found to differ markedly from site to site. Under certain conditions of pH and ionic strength, the rates for the cleavage of the DNA were the same at each recognition site. But under altered experimental conditions, different reaction rates were observed at each recognition site. These results are consistent with a mechanism in which the kinetic stability of the complex between the enzyme and the recognition site on the DNA differs among the sites, due to the effect of interactions between the enzyme and DNA sequences surrounding each recognition site upon the transition state of the reaction. Reactions at individual sites on a DNA molecule containing more than one recognition site were found to be independent of each other, thus excluding the possibility of a processive mechanism for the EcoRI enzyme. The consequences of these observations are discussed with regard to both DNA-protein interactions and to the application of restriction enzymes in the study of the structure of DNA molecules.

scholarly journals The SalGI restriction endonuclease. Enzyme specificity

1982 ◽  
Vol 203 (1) ◽  
pp. 93-98 ◽  
Author(s):  
A Maxwell ◽  
S E Halford
Keyword(s):  
Restriction Endonuclease ◽  
Dna Sequences ◽  
Dna Cleavage ◽  
Competitive Inhibition ◽  
Recognition Site ◽  
Enzyme Specificity ◽  
Recognition Sequence ◽  
Kinetics Of ◽  
Endonuclease Enzyme

We have analysed the kinetics of DNA cleavage in the reaction between the SalGI restriction endonuclease and plasmid pMB9. This reaction is subject to competitive inhibition by DNA sequences outside the SalGI recognition site; we have determined the Km and Vmax. for the reaction of this enzyme at its recognition site and the KI for its interaction at other DNA sequences. We conclude that the specificity of DNA cleavage by the enzyme is only partly determined by the discrimination it shows for binding at its recognition sequence compared with binding to other DNA sequences.

scholarly journals Two thermostable type II restriction endonucleases from Icelandic strains of the genus Thermus: Tsp4C I (ACN/GT), a novel type II restriction endonuclease, and Tsp8E I, an isoschizomer of the mesophilic enzyme Bgl I (GCCNNNN/NGGC)

1995 ◽  
Vol 309 (2) ◽  
pp. 595-599 ◽  
Author(s):  
S G Welch ◽  
R A D Williams
Keyword(s):  
Enzyme Activity ◽  
Restriction Endonuclease ◽  
Thermophilic Bacteria ◽  
Hot Water ◽  
Restriction Endonucleases ◽  
Type Ii ◽  
Endonuclease Activity ◽  
Lambda Phage ◽  
Recognition Sequence ◽  
Phosphodiester Bond

Sixteen isolates of thermophilic bacteria from the genus Thermus, isolated from neutral and alkaline hot water springs in the southwest region of Iceland, were tested for the presence of restriction endonucleases. Extracts from five of the isolates showed evidence of the presence of restriction endonuclease activity by producing discrete nucleotide fragments when incubated at 65 degrees C with lambda phage DNA. Two of the isolates (Tsp4C and Tsp8E) were found to have particularly high levels of restriction endonuclease activity, and the respective enzymes from these two Thermus isolates were partially purified and characterized and their recognition and cleavage sites were determined. Enzyme Tsp4C I is a novel Type II restriction endonuclease recognizing the interrupted palindromic tetranucleotide sequence ACNGT, where N can be any one of the four bases in DNA. Tsp4C I, which retains full enzyme activity when incubated for 10 min at temperatures up to 76 degrees C, hydrolyses the phosphodiester bond in both strands of a double-stranded DNA substrate between the third and fourth bases of the recognition sequence (ACN/GT), generating fragments with a single base 3′-OH overhang. Enzyme Tsp8E I is a thermostable isoschizomer of the mesophilic Type II restriction endonuclease Bgl I (GCCNNNN/NGGC) [Lee, Clanton and Chirikjiam (1979) Fed. Proc. 28, 294], generating fragments with a three base 3′-OH overhang. However, unlike Bgl I, Tsp8E I exhibits considerable thermal stability, retaining full enzyme activity when incubated for 10 min at temperatures up to 78 degrees C. Both Tsp4C I and Tsp8E I represent significant additions to the small but expanding list of the extremely thermostable restriction endonucleases.

NMR spectroscopic and enzymatic studies of DNA hairpins containing mismatches in the EcoRI recognition site

1998 ◽  
Vol 76 (2-3) ◽  
pp. 391-402 ◽  
Author(s):  
Markus W Germann ◽  
Bernd W Kalisch ◽  
James M Varnum ◽  
Hans J Vogel ◽  
Johan H van de Sande
Keyword(s):  
Restriction Endonuclease ◽  
Base Pair ◽  
Binding Constants ◽  
Recognition Site ◽  
Dna Hairpins ◽  
Phosphodiester Bond ◽  
Dna Oligonucleotides ◽  
Substrate Properties ◽  
Hairpin Structures ◽  
Endonuclease Ecori

We have correlated the structural perturbations caused by DNA mismatches with the enzymatic data of the interaction of the restriction endonuclease EcoRI with DNA. Oligonucleotides d(CGAGAATTCTCA5GAXAATTCT) (X = G, A, T) and d(CGCGAATTYGCGT4CGCXAATTCGCG) (Y = C, X = G, T and Y = A, X = T) containing single mismatches within the EcoRI recognition site were characterized by NMR spectroscopy and by their EcoRI substrate properties. UV melting and gel electrophoresis studies confirm that the oligonucleotides form hairpin structures. The presence of either a CT or a CA mismatch results in markedly lower Tm and van't Hoff enthalpies compared with the fully base paired control. NMR imino proton spectra of these hairpins demonstrate that the perturbation caused by the two mispairs or a noncanonical AT pair is localized and limited to one or two base pairs on either side of the perturbation. The DNA hairpin structures containing single mismatches, and to a lesser extent also sequences with a single noncanonical base pair, are substrates for the restriction endonuclease. In addition to the strand scission at the nonperturbed GpA phosphodiester bond some cleavage is observed at the mismatched position. The interactions of the CA and CT mismatched hairpin with the enzyme are characterized by binding constants that are only 33 and 57 times lower, respectively, than that for the canonical sequence, corresponding to 8-10 kJ·mol-1 less favorable free binding energy. This, taken together with the NMR data, indicates that the CA and CT mismatches have only small effects on the EcoRI recognition of the DNA substrate. We conclude that two out of the three hydrogen bonds that characterize the interaction of EcoRI with the CG base pair in the canonical sequence can still be formed for either the CT or CA mismatched recognition site.Key words: DNA hairpins, EcoRI recognition, mismatches, imino protons.

Molecular analyses of conjugative, gentamicin-resistance plasmids from staphylococcal clinical isolates

1988 ◽  
Vol 34 (9) ◽  
pp. 1050-1057 ◽  
Author(s):  
Ioannis Zorbas ◽  
Robert T. Hall ◽  
Sue L. Hall ◽  
William G. Barnes ◽  
Marvin Rogolsky
Keyword(s):  
Restriction Endonuclease ◽  
Clinical Isolates ◽  
Genetic Determinants ◽  
Conjugative Plasmids ◽  
Molecular Weights ◽  
Geographical Regions ◽  
Gentamicin Resistance ◽  
Ecori Restriction ◽  
High Degree ◽  
Endonuclease Digestion

Gentamicin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains which were isolated from infants with staphylococcal bacteremia were analyzed for the presence of self-transmissible gentamicin-resistance (Gmr) plasmids. Conjugative GMr plasmids of approximately 43.8–63 kilobases (kb) were found in all S. aureus strains. Inter- and intra-species transfer of Gmr plasmids by conjugation was observed from S. aureus to S. aureus and to S. epidermidis recipient strains. However, neither inter- nor intra-species transfer of gentamicin resistance by conjugation was observed with nine out of nine S. epidermidis donor strains which were mated with either S. epidermidis or S. aureus recipient strains. These conjugative Gmr plasmids were unable to comobilize a smaller (15-kb) plasmid present in all but two S. aureus clinical isolates. Many of the conjugative Gmr plasmids also carried genetic determinants for kanamycin, tobramycin, neomycin, and ethidium bromide resistance, and for β-lactamase synthesis. EcoRI restriction endonuclease digests of the S. aureus Gmr conjugative plasmids revealed three different digestion patterns. Four EcoRI restriction endonuclease digestion fragments of 15, 11.4, 6.3, and 4.6 kb in size were common to all plasmids. These plasmids and conjugative Gmr staphylococcal plasmids from other geographical regions shared restriction digestion fragments of similar molecular weights. DNA hybridization with biotinylated S. aureus plasmid pIZ7814 DNA revealed a high degree of homology among these plasmids. A 50.9-kb plasmid from one of the nonconjugative S. epidermidis clinical isolates showed homology with the probe DNA but lacked a portion of a 6.3-kb fragment which was present in all conjugative plasmids and believed to carry much genetic information for conjugation.

scholarly journals Identification of Simian virus 40 promoter DNA sequences capable of conferring restriction endonuclease hypersensitivity.

1996 ◽  
Vol 70 (6) ◽  
pp. 3416-3422 ◽  
Author(s):  
R Hermansen ◽  
M A Sierra ◽  
J Johnson ◽  
M Friez ◽  
B Milavetz
Keyword(s):  
Restriction Endonuclease ◽  
Dna Sequences ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Promoter Dna
Sign in / Sign up

Export Citation Format

Share Document