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Evidence for the involvement of ribonucleic acid in the production of F pili

The effects of rifampin and streptolydigin, inhibitors of ribonucleic acid (RNA) synthesis, on the production of F pili by Escherichia coli were studied by electron microscopy. The inhibition of RNA synthesis reduces the number of new pili produced by depiliated cells, but does not affect their length or the number of pili present at the time of inhibition or the retraction of pili. We suggest that the rifampin-sensitive step may be linked to the establishement of a site for pili production. Evidence is provided that chloramphenicol inhibits retraction. We suggest that retraction requires some protein whose pool size is limited.