Specific action of T4 endonuclease V on damaged DNA in xeroderma pigmentosum cells in vivo.

Abstract

The specific action of T4 endonuclease V on damaged DNA in xeroderma pigmentosum cells was examined using an in vivo assay system with hemagglutinating virus of Japan (Sendai virus) inactivated by UV light. A clear dose response was observed between the level of UV-induce unscheduled DNA synthesis of xeroderma pigmentosum cells and the amount of T4 endonuclease V activity added. The T4 enzyme was unstable in human cells, and its half-life was 3 hr. Fractions derived from an extract of Escherichia coli infected with T4V1, a mutant defective in the endonuclease V gene, showed no ability to restore the UV-induced unscheduled DNA synthesis of xeroderma pigmentosum cells. However, fractions derived from an extract of T4D-infected E. coli with endonuclease V activity were effective. The T4 enzyme was effective in xeroderma pigmentosum cells on DNA damaged by UV light but not in cells damaged by 4-nitroquinoline 1-oxide. The results of these experiments show that the T4 enzyme has a specific action on human cell DNA in vivo. Treatment with the T4 enzyme increased the survival of group A xeroderma pigmentosum cells after UV irradiation.

• Authors: K Tanaka, H Hayakawa, M Sekiguchi, Y Okada
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 74 Issue 7 Pg. 2958-62 (Jul 1977) ISSN: 0027-8424 [Print] United States
• PMID: 197527 (Publication Type: Journal Article)

Chemical References

• 4-Nitroquinoline-1-oxide
• DNA
• Endonucleases

Topics

• 4-Nitroquinoline-1-oxide (pharmacology)
• Cell Line
• Coliphages (enzymology)
• DNA (biosynthesis, metabolism)
• DNA Repair
• Endonucleases (metabolism)
• Genes
• Humans
• Parainfluenza Virus 1, Human (radiation effects)
• Ultraviolet Rays
• Xeroderma Pigmentosum (enzymology, genetics, metabolism)