Fig. 2.
Identification of proteins encoded by the repR locus of pIGRK. a Diagram of the repR locus with the position of the authentic START codon and other putative internal start codons marked, plus the location of the HindIII site used to produce a frameshift mutation. Schematic depictions of the RepR and RepR’ protein sequences with putative wHTH and coiled-coil motifs shown. Within the wHTH motif, alpha helices (α) and beta sheets (β) are indicated. Lines represent repR variants cloned in vector pET28b + in a translational fusion with a histidine tag (6His), with some color coded. Point mutations to alter the putative internal start codons are marked in red. b Western blot analysis: (1) protein molecular-weight size marker, (2–7) C-terminally His-tagged proteins detected in protein cell extracts of E. coli strains carrying pET28b+, (2) the color-coded constructs described in the panel A (3–7). Plasmid pETΔT7-repR6H carries a wild-type copy of the repR gene that is not fused to the T7 promoter; pETPrepR6H carries the repR gene under control of its native PrepR promoter