Degradation of macromolecules such as DNA, RNA, protein, and phospholipid in carotovoricin Er-treated cells was examined. No significant decrease in acid-insoluble radioactivity of DNA, RNA, or protein which were labeled with
3H-thymine,
3H-uracil, and
3H-phenylalanine, respectively, could be detected in the carotovoricin Er-treated cells. On the other hand, marked degradation of phospholipids labeled with 2-
3H-glycerol was observed in the cells exposed to the bacteriocin. There was a similar decrease in radioactivity of both
3H and
32P in the lipid fraction double-labeled with 2-
3H-glycerol and
32PO
3-4. This decrease in radioactivity of phospholipids was explained by the release of fatty acid moieties from phospholipids. These results indicate that phospholipid degradation in carotovoricin Er-treated cells is caused by the action of phospholipase A. The amount of fatty acids released from phospholipids was proportional to the number of cells killed by the bacteriocin, suggesting that phospholipase A activity involved in phospholipid degradation is located in the sensitive cells, not in the bacteriocin.
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