DIFFERENTIAL GENE-EXPRESSION FROM THE ESCHERICHIA-COLI ATP OPERON MEDIATED BY SEGMENTAL DIFFERENCES IN MESSENGER-RNA STABILITY

The atp operon of Escherichia coli directs synthesis rates of protein subunits that are well matched to the requirements of assembly of the membrane-bound H+-ATPase ((alpha-3-beta-1-delta-1-epsilon-1-a1b2c10-15). Segmental differences in mRNA stability are shown to contribute to the differential control of atp gene expression. The first two genes of the operon, atpI and atpB, are rapidly inactivated at the mRNA level. The remaining seven genes are more stable. It has previously been established that the translational efficiencies of the atp genes vary greatly. Thus differential expression from this operon is achieved via post-transcriptional control exerted at two levels. Neither enhancement of translational efficiency nor insertion of repetitive extragenic palindromic (REP) sequences into the atpIB intercistronic region stabilized atpI We discuss the implications of these results in terms of the pathway of mRNA degradation and of the role of mRNA stability in the control of gene expression.