This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wiesner, R. Articles by Troll, W. Search for Related Content PubMed PubMed Citation Articles by Wiesner, R. Articles by Troll, W.

Blocking by the Carcinogen, L-Ethionine, of SOS Functions in a tif-1 Mutant of Escherichia coli B/r¹

Department of Environmental Medicine, New York University Medical Center, New York, New York 10016

In Escherichia coli, DNA damage by carcinogenic agents results in the coordinate expression of a diversity of functions (SOS functions), many of which are thermally inducible without any damage to DNA in a tif-1 mutant. These include prophage induction, filamentous growth, and an error-prone DNA repair activity, which is responsible for ultraviolet-induced mutagenesis. Ethionine causes hepatic carcinoma in rats after prolonged feeding but is not a mutagen in the Ames test. The present study shows that 10 mM ethionine prevents the thermal induction of -prophage in a tif-1 derivative of E. coli. The enhancement of mutation, which normally occurs at high temperature after a low dose of ultraviolet light, is also blocked by ethionine. Ethionine does not block, to any appreciable extent, the incorporation of radioactive precursors into RNA, DNA, or protein.

¹ This research was supported by USPHS Grant CA 16060 and is part of a New York University Medical Center Program supported by the National Institute of Environmental Health Sciences, NIH (Grant ES 00260).

² To whom requests for reprints should be addressed.

Received 10/24/80. Accepted 7/22/81.