Respective roles of pyrimidine dimer and pyrimidine (6-4) pyrimidone photoproducts in UV mutagenesis of simian virus 40 DNA in mammalian cells

Abstract

UV light induces DNA lesions which are mutagenic in mammalian cells. We used simian virus 40 tsB201 (unable to produce viral capsid at the restrictive temperature of 41°C because of a point mutation in the VP1 gene) to analyze the mutagenic potency of the two major UV-induced lesions, pyrimidine dimers (Py-Py) and pyrimidine (6-4) pyrimidones [Py(6-4)Py], which are formed on the same nucleotide sites. The mutagenesis criterion was the reversion toward a wild-type growth phenotype. After UV irradiation (mainly at 254 nm), part of the DNA was treated with the photoreactivating enzyme of Escherichia coli, which monomerizes Py-Py but does not modify the P,(6-4)Py photoproduct. Higher survival and lower mutation frequency rates for the photoreactivated DNA indicated that the two lesions were lethal and mutagenic. The VP1 gene of some mutants was entirely sequenced. The mutation spectra showed that the two lesions did not induce the same mutation hot spots, although some sites were common to both. The induced mutation hot spots were not only correlated with lesion hot spots but seemed partially directed by local DNA structures.

Evaluating ultraviolet sensitivity of adventitious agents in biopharmaceutical manufacturing

“…There is an outlier on both the high-and low-sensitivity side. The average D 10 without these two values is 92.8 mJ/cm 2 , compared with the low of only 1.8 mJ/ cm 2 from Wang et al [110] and a high value of 301 mJ/cm 2 for Bourre et al [17]. The authors of the present review have measured the D 10 for SV40 to be approximately 100 mJ/cm 2 [89], consistent with the consensus literature value.…”

“…Most of the adventitious agents that have been identified as concerns for CHO cell processes are included in this review, but reliable UV sensitivity data for the following agents were not readily available and merit further study: bluetongue virus, bovine coronavirus, bovine polyoma virus, bovine respiratory syncytial virus, epizootic hemorrhagic disease virus, monkey pox virus, mycobacteria, and vesivirus 2117. 112 [52] 127 [19] 140 [28] 167 [91] 301 [17] 100 [89]…”

Viral inactivation by light

“…UVC damages the viral genome, but there are some reports of damage to viral proteins. In the case of DNA viruses, two major UV-induced lesions, pyrimidine dimers (Py-Py) and pyrimidine (6–4) pyrimidones [Py(6–4)Py], which arise at the same nucleotide sites, are lethal and mutagenic [ 43 , 44 ]. In contrast, RNA differs from DNA mainly in the presence of uracil nucleotides instead of thymine.…”

Formation and Processing of UV Photoproducts: Effects of DNA Sequence and Chromatin Environment

“…These experiments have generally indicated the presence of mutation hotspots often associated with sequences of adjacent pyrimidines (e.g. [170][171][172]. Shuttle vector experiments suffer from some potential problems.…”