Purification of the gene 0. 3 protein of bacteriophage T7, an inhibitor of the DNA restriction system of Escherichia coli

Journal Article · Tue Mar 10 04:00:00 EST 1981 · J. Biol. Chem.; (United States)

OSTI ID:6461653

Mark, K K; Studier, F W

The gene 0.3 protein of bacteriophage T7 prevents the DNA restriction system of Escherichia coli from interfering with T7 infection. A mutant strain of T7 that greatly overproduces the 0.3 protein has been constructed and used for purification of this protein. The 0.3 protein was found to be extremely acidic and can be separated from virtually all other proteins of the infected cell by chromatography on DEAE-cellulose. Residual contaminating proteins and nucleic acids can be removed by gel filtration, but an even simpler final purification is possible, because under appropriate conditions the 0.3 protein is soluble in high concentrations of ethanol. Thus, a simple, essentially two-step purification can produce about 50 mg of pure 0.3 protein from 30 liters of culture. The purified protein appears to be a dimer of identical subunits. As expected from its known function during infection, the purified 0.3 protein inhibits the nuclease and ATPase activities of partially purified Eco B, the DNA restriction enzyme of E. coli B, but it does not interfere with several different type II restriction endonucleases tested. The inhibition of Eco B appears to require stoichiometric rather than catalytic amounts of 0.3 protein.

• Research Organization: Brookhaven National Lab., Upton, NY
• OSTI ID: 6461653
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 256:5; ISSN JBCHA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BACTERIOPHAGES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DNA
ENZYME ACTIVITY
ESCHERICHIA COLI
EVEN-ODD NUCLEI
FILTRATION
GENES
INHIBITION
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MICROORGANISMS
MUTANTS
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
PROTEINS
PURIFICATION
RADIOISOTOPES
SEPARATION PROCESSES
SULFUR 35
SULFUR ISOTOPES
VIRUSES