Analysis of the mutations induced in the E. coli lac Z gene by a psoralen analog.
A psoralen in which intracyclic oxygen atoms were replaced by sulfur (7H-thieno [3,2-g]-[1]-[benzothiopyran-7-one) [PSO(S-S)]) was recently synthesized and its photobiological properties were investigated. M13mp19 DNA photosensitization mediated by PSO (S-S) followed by transfection into competent E. coli gave rise to a very low phage progeny showing the high aptitude of this compound to modify DNA. In order to characterize the role of oxidative damages in the photosensitized reaction mediated by PSO(S-S), plasmid bearing the gene encoding the formamidopyrimidine DNA glycosylase (Fpg) under the control of the inducible lac Z promoter was transfected in E. coli. Overexpression of Fpg was induced by addition of isopropyl-beta-D-thio-galactopyranoside (IPTG) to the cells and monitored by western blot analysis. Fpg overexpression did not influence the rate of M13mp19 DNA photoinactivation by PSO(S-S) neither the mutation frequency measured by the expression of beta-galactosidase encoded by the lac Z gene beared by M13mp19. Analysis of the mutation patterns recorded with or without Fpg overexpression showed that several G to T transversions due to oxidative damages were repaired by Fpg. These data show that oxidative DNA damages generated during PSO(S-S) photosensitization have only limited biological implications measured in terms of DNA photoinactivation.
Matroule
J Y
JY
Laboratory of Virology, Institute of Pathology B23, University of Liège, Belgium.
Collet
M
M
Boiteux
S
S
Piette
J
J
D017104:Bacteriophage M13 / Q000235:genetics; D001483:Base Sequence; D004279:DNA, Viral / Q000528:radiation effects*; D043382:DNA-Formamidopyrimidine Glycosylase; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005363:Ficusin / Q000737:chemistry; D011564:Furocoumarins; D015870:Gene Expression; D007763:Lac Operon; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009699:N-Glycosyl Hydrolases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism
D004279:DNA, Viral; D029968:Escherichia coli Proteins; D011564:Furocoumarins; D017319:Photosensitizing Agents; D011993:Recombinant Fusion Proteins; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D005363:Ficusin