Effects of the unc I gene on expression of unc B, the gene coding for the a subunit of the F 1 F 0 ATPase of Escherichia coli

The eight genes coding for the subunits of the E. coli F 1 F 0 ATPase are preceded by a gene, designated unc I. A homologous gene, or a gene coding for an analagous protein, is found preceding the ATPase genes of several microorganisms. No function for the I gene has been described. Using lac fusions to measure gene expression in vivo, we tested the effects of deleting unc I on the expression of the adjacent gene unc B, which codes for the a subunit of the F 0 sector of the ATPase. Deleting unc I reduced the expression of three unc B′‐′ lac Z fusion genes in vivo, but had no effect on the expression of two unc B′‐′ lac Z fusion genes containing a relatively smaller amount of the unc B coding region. The unc I deletion also reduced the relative synthesis of the a subunit in vitro. The I gene therefore appears to specifically affect the expression of unc B or the synthesis of the a subunit at some step after translational initiation of unc B.