Fast Translation within the First 45 Codons Decreases mRNA Stability and Increases Premature Transcription Termination in E. coli

摘要

We show here that the specific use of fast or slowly translated codons in the early coding region of a gene may influence both the mRNA stability and premature transcription termination. We first inserted a pair of nearly identical 42-base-pair (bp)-long sequences into codon 3 of the Escherichia coli lacZgene. The only difference between the two inserts was that the first base in one was moved to become the last base in the other, providing a difference in the reading frame, one of which had the biased codons typical for ribosomal protein genes and which previously was shown to be faster translated than average. This insert reduced the mRNA stability and increased premature transcription termination and together resulted in a hundred-fold difference in lacZ expression. We next generated lacZ variants with 7, 14 or 21 fast translated, ribosomal-type codons inserted into codon 13 of lacZ.