Fig. 1.

Components of in vivo assay systems used in this study.

A. Activity of σ³²-dependent promoters in the presence of σ³² variants was determined by β-galactosidase assay from the ΔrpoH strain CAG57101 carrying the plasmids pSAKT32 and pQF50K. σ³² expression was induced from pSAKT32 and derivatives (pBK116–pBK151), which has a p15A replication origin and rpoH under control of the lac promoter. Note that most of the σ³² derivatives contain the additional substitution I54N that improves stability and decreases negative regulation. The reporter plasmid, pQF50K and derivatives (pBK501–pBK549), has a pMB1 replication origin and lacZ under control of σ³² promoter.

B. Sequences of σ³²-dependent promoters used in this study. Only wt sequences of each promoter are shown: single- or double-base changed promoter mutants were constructed from these parent promoters. The native sequences of the groE and grpE promoter regions are shown in capital letters; vector sequences are in lower case; BglII and XbaI cloning sites are underlined; −35 and −10 regions, and the