Distribution of ultraviolet-induced DNA repair synthesis in nuclease sensitive and resistant regions of human chromatin

Journal Article · Tue Jun 13 00:00:00 EDT 1978 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00605a020· OSTI ID:6687599

Smerdon, M J; Tlsty, T D; Lieberman, M W

The distribution of ultraviolet radiation (uv) induced DNA repair synthesis within chromatin was examined in cultured human diploid fibroblasts (IMR-90). Measurement of the time course of repair synthesis yielded two distinct phases: An initial rapid phase (fast repair) which occurs during the first 2 to 3 h after damage and a slower phase (slow repair) associated with a tenfold decrease in the rate of nucleotide incorporation, which persists for at least 35 h after damage. Staphylococcal nuclease digests of nuclei from cells damaged with uv and labeled during the fast-repair phase revealed a marked preference of fast-repair synthesis for the nuclease-sensitive regions. A new method was developed to analyze the digestion data and showed that approximately 50% of the nucleotides incorporated during the fast-repair phase are located in staphylococcal nuclease-sensitive regions, which comprise about 30% of the genome. Calculations from these data indicate that in the staphylococcal nuclease-sensitive regions the number of newly inserted nucleotides per unit DNA is about twice that of resistant regions. These results were supported by electrophoresis studies which demonstrated a decreased representation of fast-repair synthesis in core particle DNA. In contrast, the distribution within chromatin of nucleotides incorporated during the slow-repair phase was found to be much more homogeneous with about 30% of the repair sites located in 25% of the genome. Digestion studieswith DNase I indicated a slight preference of repair synthesis for regions sensitive to this enzyme; however, no marked difference between the distributions of fast- and slow-repair synthesis was observed. This study provides evidence that the structural constraints placed upon DNA in chromatin also place constraints upon uv-induced DNA repair synthesis in human cells.

• Research Organization: Washington Univ., St. Louis
• OSTI ID: 6687599
• Journal Information: Biochemistry; (United States), Vol. 17:12
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL REPAIR
DNA REPLICATION
CHROMATIN
MOLECULAR STRUCTURE
DNA
BIOLOGICAL RADIATION EFFECTS
FIBROBLASTS
NUCLEOTIDES
SENSITIVITY
CELL CULTURES
IRRADIATION
MAN
NUCLEASES
ULTRAVIOLET RADIATION
ANIMAL CELLS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
CONNECTIVE TISSUE CELLS
ELECTROMAGNETIC RADIATION
ENZYMES
MAMMALS
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PHOSPHOTRANSFERASES
PRIMATES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SOMATIC CELLS
TRANSFERASES
VERTEBRATES
560121* - Radiation Effects on Cells- External Source- (-1987)
550300 - Cytology
550200 - Biochemistry