Biomaterial Database

Biochemical characterization of the restriction-modification system of Bacillus sphaericus. 1978

C Koncz, and A Kiss, and P Venetianer

A type II restriction endonuclease (endo R . Bsp) has been purified from Bacillus sphaericus to electrophoretic homogeneity. The enzyme appears to be a single polypeptide chain with a molecular weight of 35000. Its pH optimum is around 8.2, it requires 20 mM Mg2+ for optimal activity and it is inhibited by Zn2+. The yield of the enzyme is higher than that of any type II restriction endonuclease so far reported. The enzyme also cleaves single-stranded DNA, albeit at a slower rate. It seems likely that single-stranded DNA is cleaved at the same sequences as double-stranded DNA. Bacillus sphaericus also contains a modification methylase (meth M . Bsp) which completely protects the cell's own DNA against cleavage by its restriction endonuclease. The methylase activity has been partially purified, it copurifies with the nuclease until the next to the last step. The enzyme does not require ATP or Mg2+, it transfers the methyl group of S-adenosyl-methionine to cytosine residues of DNA. As the action of this methylase completely protects any DNA from endo R . Bsp cleavage, it seems likely that the methylase recognizes and methylates the same sequence (dG-dG-dC-dC) as the nuclease.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D004248	DNA (Cytosine-5-)-Methyltransferases	Enzymes that catalyzes the transfer of a methyl group from S-ADENOSYLMETHIONINE to the 5-position of CYTOSINE residues in DNA.	DNA (Cytosine-5-)-Methyltransferase,DNA Cytosine-5-Methylase,DNA (Cytosine 5) Methyltransferase,Cytosine-5-Methylase, DNA,DNA Cytosine 5 Methylase
D004262	DNA Restriction Enzymes	Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.	Restriction Endonucleases,DNA Restriction Enzyme,Restriction Endonuclease,Endonuclease, Restriction,Endonucleases, Restriction,Enzymes, DNA Restriction,Restriction Enzyme, DNA,Restriction Enzymes, DNA
D004355	Drug Stability	The chemical and physical integrity of a pharmaceutical product.	Drug Shelf Life,Drugs Shelf Lives,Shelf Life, Drugs,Drug Stabilities,Drugs Shelf Life,Drugs Shelf Live,Life, Drugs Shelf,Shelf Life, Drug,Shelf Live, Drugs,Shelf Lives, Drugs
D001407	Bacillus	A genus of BACILLACEAE that are spore-forming, rod-shaped cells. Most species are saprophytic soil forms with only a few species being pathogenic.	Bacillus bacterium
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities