Yuji Higo

Biological threshold values of procaryotic gene expression which is controlled by the DNA inverted repeat sequence and the mRNA secondary structure

Abstract Procaryotic gene expression is generally controlled at three levels, i.e., transcription, translation and degradation of mRNA. The effects of the DNA inverted repeat sequence and the mRNA secondary structure on each step in the gene expression were analyzed by the compilation of quantitative data published in the literature. When the ΔG of the mRNA secondary structure in an SD sequence and the flanking region is larger (i.e., more negative) than −5∼−6 kcal/mol, the efficiency of translation initiation drops drastically to 30% or less of the full expression. When the ΔG values of mRNA secondary structures in an open reading frame, the 3′-terminus region and the inverted repeat sequence of the terminator are larger than −20 kcal/mol, reduction of translation efficiency, mRNA stability, and transcription termination are maximized, respectively. In other words, the biological threshold values of the mRNA secondary structure for the regulation of translation initiation and other steps (termination of transcription, degradation of mRNA, and elongation of peptide chain) are −5∼−6 kcal/mol and −20 kcal/mol in ΔG value, respectively. Reasons for the difference are discussed.