Nucleic Acids Research, 1988, Vol. 16, No. 21 9961-9977
© 1988
CHEMISTRY |
Mutagenesis induced by site specifically placed 4'-hydroxymethyl-4,5',8-trimethylpsoralen adducts
Laboratory of Experimental Physics, University of LiÈge B4000 LiÈge, Belgium 1Microprobe Corporation Bothell, WA 98021, USA 2Department of Chemistry, University of California Berkeley, CA 94720, USA
*To whom correspondence should be addressed
Received August 30, 1988. Accepted October 10, 1988.
Closed circular double stranded M13mp19 DNA containing a site-specifically placed HMT (4'-hydroxymethyl-4-5'-8-trimethylpsoralen) monoadduct or crosslink was synthesized in vitro. The damaged DNA were scored for loss of infectivity by transfection into repair proficient or deficient E. coli and into SOS induced E. coli Mutant phages were detected by the loss of 
-complementation between the viral and the host Lac Z genes or by the acquisition of resistance to kpn I digestion. Our results indicate that HMT mutagenesis is targeted and that deletion or transversion of the modified thymidine is the predominant sequence change elicited by a monoadduct or a crosslink. Transfection of the monoadducted DNA into a Uvr A deficient strain did not change the mutation pattern but did increase the respective mutation frequencies. Transfection of the crosslinked DNA into a SOS induced host resulted in the appearence of other types of mutations attribuable to an increase in both targeted and untargeted mutations.