Effects of vacuum UV and UVC radiation on dry Escherichia coli plasmid pUC19 II. Mutational specificity at the lacZ gene

✍ Scribed by Jörg Wehner; Gerda Horneck

• Book ID: 103994608
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 751 KB
• Volume: 30
• Category: Article
• ISSN: 1011-1344
• DOI: 10.1016/1011-1344(95)07158-x

✦ Synopsis

The mutational spectra at the lacZ gene, induced either by vacuum UV at 160 nm or UVC at 254 nm in vacuum-dried preparations of Escherichia coli plasmid pUC19 DNA, have been characterized from 72 E. coli-propagated mutants by DNA sequencing. In plasmids irradiated in vacuum, vacuum UV is five times more mutagenic than UVC. In the UV-induced mutants, base substitutions largely predominate, with GC-->AT (G, guanine; C, cytosine; A, adenine; T, thymine) transitions being the most abundant type of base change for vacuum UV (61%) and UVC (47%). Most of the GC-->AT transitions appear to occur at dipyrimidine sites, which are located at the non-transcribed DNA strand. Some, but not all, hot spots for GC-->AT transitions are identical for vacuum UV and UVC. Frameshifts, resulting from a loss of the thymine residue, are specific for UVC (22%), and were not detected after treatment with vacuum UV. They occur predominantly at thymine runs of the transcribed DNA strand. Only a few deletions were detected following irradiation with vacuum UV (7.5%) and UVC (2%); however, their frequency is not enhanced compared with the spontaneous mutation spectrum. The data confirm the important role of base substitution mutations in UV-induced mutagenesis, which is not only valid for the UVC range, but extends towards the vacuum UV range.