[New method of construction of artificial translational-coupled operons in bacterial chromosome].

The new method of translational-coupled operons construction in bacterial chromosome has been developed on the basis of recombineering approach. It includes construction in vitro of the artificial operon with efficiently translated proximal cistron followed by its insertion E. coli chromosome, modification of the operon due to Red-driven insertion of the special "Junction" with excisable selective marker in the intercistronic region of the initial operon and excising the marker. The structure of this Junction has been designed and tested in the present investigation. It consists of: 1) E. coli rplC-rplD intercistronic region for placing the TAA-codon of the proximal operon's gene in the SD-sequence (TAAGGAG) of rplD; 2) Cm(R)-gene flanked by lambdaattL/R-sites in such a fashion that after lambdaInt/Xis-driven excision of the marker the residual lambdaattB-site would not contain the termination codons in frame with ATG of rplD; 3) E. coli trpE-trpD intercistronic region for location of ATG of trpD at the position of initiation codon of the distal gene of original operon. The general design of desired construction provides the conversion of the original two-cistronic operon into three-cistronic operon with translational-coupled genes, where the coupling of the artificial ORF (rplD'-lambdaattB-'trpE) with the proximal gene is occurred due to rplC-rplD intercistronic region and the coupling of this ORF with the distal gene--due to trpE-trpD. The experimental implementation of the described strategy was showed by construction of artificial operon P(tac-aroG4-serA5, where expression optimization of the distal serA5 gene was achieved via construction of three-cistronic operon with translational-coupled genes.