Flagellar synthesis in Salmonella typhimurium: requirement for ribonucleic acid synthesis.

The micro-complement-fixation assay has been demonstrated to be a sensitive assay for flagella which occur in nanogram amounts. By use of this assay, it was found that flagellar synthesis occurs during starvation of Salmonella typhimurium for tryptophan, an amino acid not present in flagellar protein. Under these conditions net ribonucleic acid (RNA) synthesis was reduced to approximately 10% of the control rate. Less than 1 mug of actinomycin D per ml further reduced RNA synthesis to less than 1% of the control rate in a culture sensitized by prior treatment for 5 min at 37 C with 5 x 10(-4)m ethylenediaminetetraacetate in 0.33 m tris(hydroxymethyl)aminomethane-chloride (pH 8.0). In the presence of actinomycin D, no synthesis of flagellar protein could be detected. Analysis of fractions of RNA separated by zone centrifugation indicated that actinomycin D reduces the production of template RNA as well as of ribosomal RNA. This suggests that in S. typhimurium the production of flagellar protein requires the concomitant synthesis of RNA. There is no evidence that a stable messenger RNA specific for flagellar synthesis is present.