Secondary structure as primary determinant of the efficiency of ribosomal binding sites in Escherichia coli

Using a previously described vector (pKL203) the authors fused several heterologous ribosomal binding sites (RBSs) to the lacZ gene of E. coli and then studied the variation in expression of fusions. The RBSs originated from bacteriophage Q beta and MS2 gene and the E. coli genes for elongation factor EF-Tu A and B and ribosomal protein L11 (rp1K). The synthesis of the lacZ fusion proteins was measured by an immuno precipitation method and round to vary at least 100-fold. Deletion mutations, created in the phage Q beta replicase RBS, reveal a complex pattern of control of expression, probably involving the use of a "false" initiation site.