Abstract
I have isolated a number of mutants from Escherichia coli K-12 which are highly resistant to showdomycin [2-(β-D-ribofuranosyl)maleimide]. These mutants were very sensitive to N-ethylmaleimide, which has a structure similar to the aglycone moiety of showdomycin. These mutants took up little 14C-labeled showdomycin and showed altered ability to take up various labeled nucleosides. However, their ability to take up cytosine arabinoside-3H remained essentially the same as that of the parent strain. The ability of caffeinetreated mutant cells to take up adenosine-3H was very much lower than that of caffeine-treated parent cells. The nature of deoxycytidine-14C uptake by mutant cells was markedly different from that by parent cells.
