3’UTR Engineering to Improve Functional Expression of Insoluble and/or Structurally Unstable Enzymes and Proteins in Escherichia coli

3’-Untranslated region (3’UTR) engineering was investigated to improve solubility and functional expression of insoluble and/or structurally unstable enzymes and proteins in Escherichia coli. Insertion of the gene fragments containing putative RNase E recognition sites into the 3’UTR of the target genes (e.g., Baeyer-Villiger monooxygenase (BVMO) genes) led to reduction of the corresponding mRNA level in E. coli. However, the amount of BVMOs in soluble fraction was remarkably enhanced resulting in a proportional increase of in vivo catalytic activity. The increase of biocatalytic activity notably correlated to the number of putative RNase E endonucleolytic cleavage sites in the 3’UTR. For instance, biotransformation activity of the BmoF1 of Pseudomonas fluorescens DSM50106 in E. coli was linear to the number of RNase E cleavage sites in the 3’UTR. Thereby, it was assumed that 3’UTR engineering could be used to improve soluble expression of heterologous enzymes as well as to fine-tune the enzyme activity in microbial cells.