FIG. 5.

Binding of CrtJ to the promoter region of the crtD and crtE genes. (A) The intergenic region between the divergent crtE and crtD genes, where the relevant region of this fragment is displayed. The putative −10 and −35 promoter regions are underlined. The arrows indicate putative CrtJ palindrome recognition sites. (B) Gel retardation assay with the recombinant CrtJ. A 120-bp BamHI-HindIII fragment containing the crtE-crtD intergenic region (the region used is in boldface in panel A) was isolated and labeled with α-³⁵S-dATP (see Materials and Methods). This labeled fragment was incubated with various amounts of Rhodobacter capsulatus CrtJ protein overexpressed and purified in E. coli and loaded onto a 6% native polyacrylamide gel (see Materials and Methods). Lane 6, control lane containing only the free DNA probe. Lanes 1 to 5, the DNA probe was incubated with increasing amounts (0.05, 0.11, 0.23, 0.45, and 0.9 μg, respectively) of pure CrtJ.