FIG. 2.

Construction of gene fragments specifying IIA^LacS. The 4.1-kb EcoRI chromosomal DNA fragment of pSKE8, containing the lacS gene of S. thermophilus, is shown. Only relevant restriction sites are indicated. Shown are the lacS promoter (P_s), the lacS gene (arrow), wild-type protein and portions of the IIA domain (bars). The putative linker and flanking regions are indicated by their amino acid sequences. Amino acids that frequently occur in a Q linker are marked by asterisks, and the residues following the Met of IIA^LacS[181], IIA^LacS[173], and IIA^LacS[154] are indicated by the corresponding numbers. Phosphorylation of the protein was performed in the presence of enzyme I, HPr, and PEP (for details, see Materials and Methods). The ability of LacS to become phosphorylated by HPr∼P was taken from reference 19.