FIG. 6.

Upstream elements required for dofA expression. (A) Schematic diagram of the dofA regulatory region (upper part of diagram) and structures of various dofA-lacZ fusions. The transcription initiation site is indicated as +1. Putative −35 and −10 sequences and putative regulatory sequences are indicated by open bars with nucleotide sequences. The indicated DNA segments were amplified by PCR and inserted into pSI1403attP. The resultant plasmids were introduced into the attB site of the M. xanthus chromosome to give MxDA series strains. MxDA1022 and MxDA1038 lacked the DNA segments indicated by parentheses. (B) lacZ expression under the control of various segments of the dofA regulatory region. The specific activities of β-galactosidase (averages of four independent experiments) in developing cells (20 h poststarvation) of the indicated M. xanthus strains were measured. MxVEC carried pSI1403attP. ONP, o-nitrophenol.