Incorporation of 5-Diazouracil- 2 - ¹⁴ C into Ribonucleic Acids of Escherichia coli During Division Inhibition

Abstract

Radioactive diazouracil (DZU-2-14C) was rapidly incorporated into acid-insoluble material of Escherichia coli B. Isolated ribonucleic acid contained essentially all of the incorporated label, and this was solubilized by ribonucleases but not by deoxyribonuclease. A maximum of 45 to 50% of added label was incorporated at division-inhibitory and subinhibitory concentrations. Incorporation levels and filament-forming capacity were concomitantly depressed by preincubation of DZU in various medium components. The lower levels of incorporation brought about by preincubation were apparently related to an inherent instability or high reactivity of the DZU. The limit on incorporation of fresh DZU suggests the presence of geometrical isomers in the original DZU. The nature of these isomers and the reactivity of DZU are discussed in relation to its use in future cell division studies.2-'4C and nonradioactive DZU synthesized by this procedure had matching infrared spectra. Two possible forms of the product, a hydrate and an anhydride, are shown in Fig.

Characterization of Labeled Residues from 5-Diazouracil- 2 - 14 C Incorporated into Ribonucleic Acids of Filamentous Escherichia coli

“…Cell division of Escherichia coli and some other bacteria is effectively inhibited by 5-diazouracil (DZU) with minimal aberration of other growth parameters (5,8). We have been investigating the mechanism of action of DZU (4,5) toward an understanding of division control mechanisms. Previc and Richardson (5) found that the patterns for increase in protein, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and mass were altered only slightly in cultures treated with a division-inhibitory dose (0.5 yg/ml), when compared to untreated cultures.…”

“…E. coli B, U-(pyrimidine-requiring, obtained from E. Ehrenfeld) was grown in a similar manner in MSG supplemented with uracil or cytosine (2 X 10-4 M, unless othewise FISTER, PREVIC, AND RICHARDSON by New England Nuclear Corp., Boston, Mass. The preparation and composition of the DZU has been described previously (4). Cytosine-2-14C (specific activity, 29.9 Ci/mole), adenine-8-'4C (specific activity, 4.1 Ci/mole), and guanine-8-14C (specific activity, 7.81 Ci/mole) were also obtained from New England Nuclear.…”

“…Other experimental procedures. The determination of cell numbers, incorporation of radioactivity, and the preparation of RNA from cytoplasmic extracts have been previously described (4,5).…”