| Abstrakt: |
We recently reported that a ribosome binding site (RBS) derived from gene 10of bacteriophage T7 (g10-L) causes a pronounced stimulation of expression when placed upstream of a variety of genes, and that this effect is probably due to a stimulation of translation efficiency in Escherichia coli(Olins, P. O., Devine, C. S., Rangwala, S. H., Kavka, K. S. (1988) Gene(Amst.)73, 227–235). Here we present a model for the mechanism of action of the g10-L: the RBS contains a 9-base sequence which has the potential for forming a novel base-paired interaction with bases 458–466 of the 16 S rRNA of E. coli. Although such sequence homologies are rare in E. coliRBS regions, a number of similar sequences were found in the RBS regions of other bacteriophage structural genes. When an isolated homology sequence was placed upstream of a synthetic RBS, there was a 110-fold increase in the translation efficiency of the lacZgene. Surprisingly, the homology sequence also stimulated translation when placed downstream of the initiator codon, indicating that this sequence is acting as a translational “enhancer.” |
