FIG. 1.

Folate, mtr, trp, yhaG, and yczA-ycbK operons. trpG is located within the folate operon, while the rest of the trp genes are clustered in the trpEDCFBA operon. yhaG encodes a putative tryptophan transport protein. mtrB encodes TRAP, while yczA encodes the AT protein (41). TRAP is responsible for regulating expression of the trp operon by transcription attenuation and a translational control mechanism. TRAP regulates translation of trpG, yhaG, and probably ycbK. P> marks the position of the promoters for each operon, while the black boxes show the positions of the TRAP binding sites. The positions of terminator hairpins (open circles) and antiterminator hairpins (filled circles) are shown.