title: The effect of U.V.-irradiation on lambda DNA transcription.
abstract: The effect of U.V.-irradiation of template DNA has been studied in vitro in the E. coli RNA polymerase system with native and U.V.-treated lambda DNA. Lambda DNA is more susceptible to U.V. than is calf-thymus DNA, yet a residual activity is observed at a U.V. dose of 0-5+10(4) erg/mm2. From the kinetic analysis of the reaction and the incorporation of lambda 32P-labelled nucleoside triphosphates, it seems reasonable to conclude that U.V.-irradiation probably does not affect the DNA initiation sites, recognizable by RNA polymerase. The transcription products made with U.V.-irradiated lambda DNA are assymmetrical, and hybridized to the right half (R) and the left half (L) of lambda DNA with the ratio of R/L = 4/1, and they show a lower hybridizability than the transcripts with native lambda DNA. The initiation sites recognizable by RNA polymerase seem to be the same on both native and U.V.-irradiated lambda DNA though the transcription of U.V.-treated lambda DNA appears to terminate with rather short RNA chains.
mesh_terms: D003090:Coliphages; D004279:DNA, Viral / Q000528:radiation effects*; D012321:DNA-Directed RNA Polymerases; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000201:enzymology; D014158:Transcription, Genetic / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D004279:DNA, Viral; D012321:DNA-Directed RNA Polymerases