Enzymic mechanism of excision-repair in T4-infected cells

Conference · Wed Jan 01 04:00:00 EST 1975

OSTI ID:4126250

Sekiguchi, M; Shimizu, K; Sato, K; Yasuda, S; Ohshima, S; Hanawalt, P C ^[1]

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1. ed.

Excision of pyrimidine dimers from ultraviolet-irradiated DNA in a cell- free system of Escherichia coli infected with bacteriophage T4 consists of two different steps, one to induce a single-strand break at a point close to a pyrimidine dimer and the other to release dimer-containing nucleotide from the DNA. The enzymes responsible for these steps were isolated and the reactions were characterized; T4 endonuclease V introduces a break at the 5' side of a dimer and 5' $Yields$ 3' exonucleases, which are also induced by T4, act at the break to excise dimer-containing nucleotides. We isolated temperature-dependent $nu$ mutants, which exhibit increased sensitivity to uv at 42$sup 0$C but not at 30$sup 0$C, and found that the mutants induce temperature-sensitive T4 endonuclease V, indicating that the $nu$ gene of T4 is indeed the structural gene for T4 endonuclease V and that the enzyme is responsible for the first step of excision-repair. A possible mechanism of excision-repair in T4-infected cells is discussed. (auth)

• Research Organization: Kyushu Univ., Fukuoka
• NSA Number: NSA-33-012262
• OSTI ID: 4126250
• Country of Publication: United States
• Language: English

Related Subjects

*BACTERIOPHAGES-- BIOLOGICAL RADIATION EFFECTS
*DNA-- STRAND BREAKS
*ESCHERICHIA COLI-- BIOLOGICAL RADIATION EFFECTS
*NUCLEASES-- BIOLOGICAL EFFECTS
*STRAND BREAKS-- RADIOINDUCTION
560131* --Biomedical Sciences
Applied Studies--Radiation Effects--Radiation Effects on Microorganisms--Basic Studies
DIMERS
MUTANTS
N48110 --Life Sciences--Radiation Effects on Biochemicals--In-Vitro
N48310* --Life Sciences--Radiation Effects on Microorganisms- -Basic Studies
NUCLEOTIDES
PYRIMIDINES
ULTRAVIOLET RADIATION