Effects of deletions in the uncA-uncG intergenic regions on expression of uncG, the gene for the gamma subunit of the Escherichia coli F1Fo-ATPase.

The gamma subunit of the E. coli F1Fo-ATPase is coded for by uncG. This gene is poorly expressed compared to uncA (alpha subunit), which precedes uncG in the unc operon. The genes are separated by a 50-nucleotide intergenic region. We examined the effects of a set of deletions in this region on the relative expression of uncA'-'lacZ and uncG'-'lacZ translational fusion genes located either in the chromosomal unc operon or at the chromosomal lambda att site. The gene for the alpha subunit was expressed 3-6-times better than the gene for the gamma subunit, depending upon chromosomal location. Deletion analysis revealed that the uncA-uncG intergenic region significantly affects expression of uncG, but the Shine-Dalgarno region is not absolutely required for expression of uncG. Different deletions resulted in either increased or decreased expression of uncG.