FIG. 6.

Random mutational analysis of the proposed PucR box in the pucH and pucR regulatory region. Part of the pucH-to-pucR intercistronic region is presented as a double-stranded DNA sequence. The pucH′-lacZ fusion strains (the upstream and downstream sequence fusion points are −110 and +97) are listed above the double-stranded DNA sequence, and the pucR′-lacZ fusion strains (the upstream and downstream sequence fusion points are −123 and +84) are listed below. The PucR box (5′-WWWCNTTGGTTAA-3′) and TnrA/GlnR box (5′-TGTNAN₇TNACA-3′) are listed (boldface indicates a match to the consensus sequence), and the −10 and −35 sequences and the +1 positions are indicated. Cells containing the various lacZ fusions were grown under nitrogen-limiting conditions (glutamate) either with or without allantoin. wt, wild type.