Starvation for
histidine prevented tumbling in Salmonella typhimurium hisF auxotrophs, including constantly tumbling strains with an additional mutation in
cheB or cheZ. However,
histidine-starved cheZs hisF strains were not defective in flagellar function or the tumbling mechanism since freshly starved auxotrophs tumbled in response to a variety of repellents. Tumbling in
histidine-starved S. typhimurium could be restored in 13 s by addition of
adenine or in 4 min by addition of
histidine.
Chloramphenicol did not prevent restoration of tumbling by these substances. Assays of
adenosine 5'-triphosphate were performed based upon previous demonstration of
adenine depletion in hisF auxotrophs starved for
histidine. The
adenosine 5'-triphosphate concentration dropped rapidly during the course of
starvation, falling to less than 5% of the initial level as the cells ceased tumbling entirely. The change to smooth motility was prevented by
2-thiazolealanine, which inhibits phosphoribosyltransferase, thereby preventing
adenine depletion during
histidine starvation. These results suggest that an
adenosine 5'-triphosphate deficiency was responsible for the change in tumbling frequency.