Removal of T4 endonuclease V-sensitive sites from SV40 DNA after exposure to ultraviolet light

Beyond xeroderma pigmentosum: DNA damage and repair in an ecological context. A tribute to James E. Cleaver

The ability to repair DNA is a ubiquitous characteristic of life on Earth and all organisms possess similar mechanisms for dealing with DNA damage, an indication of a very early evolutionary origin for repair processes. James E. Cleaver's career (initiated in the early 1960s) has been devoted to the study of mammalian ultraviolet radiation (UVR) photobiology, specifically the molecular genetics of xeroderma pigmentosum and other human diseases caused by defects in DNA damage recognition and repair. This work by Jim and others has influenced the study of DNA damage and repair in a variety of taxa. Today, the field of DNA repair is enhancing our understanding of not only how to treat and prevent human disease, but is providing insights on the evolutionary history of life on Earth and how natural populations are coping with UVR-induced DNA damage from anthropogenic changes in the environment such as ozone depletion.

Two proteins of 220 kD and 230 kD bind to UV-damaged SV40 minichromosomes in irradiated monkey kidney cells

We exposed SV40-infected monkey kidney cells to 0, 30 or 150 J/m2 of UV-radiation, and isolated viral minichromosomes at various times after irradiation. Analysis of minichromosome-associated proteins by SDS-PAGE revealed the presence of two proteins, of 220 kD and 230 kD associated with minichromosomes from irradiated cells, but not from unirradiated controls. The larger protein was the less abundant, and was most evident in preparations from more heavily irradiated cells. Neither protein was associated with minichromosomes isolated 30 min after irradiation, but were apparent in minichromosome preparations isolated 1-4 h after UV treatment.

Ultraviolet irradiation inhibits encapsidation of simian virus 40 chromatin

During normal maturation and majority of pulse-labeled simian virus 40 DNA progresses from chromatin to previrions and virions within 5 h. UV light inhibits this progression. In heavily irradiated cultures (108 J m-2) most of the simian virus 40 DNA synthesized immediately before irradiation remains as chromatin for at least 5 h. This inhibition of maturation seems to be a result of the inhibition of protein synthesis. The data suggest that the pool of proteins required for maturation is sufficient to convert one-third of the simian virus 40 DNA molecules labeled in a 10-min pulse (at 33 h postinfection) from chromatin to previrions and virions and is exhausted within 1 h.