FIG. 7.

Repression of expression of the V. vulnificus putAP operon by glutamate. Samples were removed from the culture of ATCC 29307 grown to log phase in M9 medium supplemented with 200 mM proline and various levels of glutamate as indicated. Samples were analyzed for determination of proline dehydrogenase activity (A) and put transcripts (B and C). Means ± SEM (error bars) are shown. PUTAP was used as a DNA probe, and the Northern blot is presented as described in the legend to Fig. 3. The relative amounts of the put transcripts in each band are expressed relative to the amount of transcript A as expressed in the absence of glutamate.