Fig. 1.

Experimental design and DNA sequence of the dicistronic constructs used in this study. a Schematic diagram of the dicistronic expression vector pO-RFP. RBS, ribosome-binding site; MCS, multiple cloning sites; ORF, open reading frame. b pO-RFP cloning/expression region. One/two/three consecutive rare codons were introduced into ORF1 of pO-RFP after EcoRI site, generating pOI-RFP/pOII-RFP/pOIII-RFP vector. c Schematic diagram of the dicistronic expression vector pGFP-RFP. The DNA fragment containing the eGFP coding sequence was directly ligated in pO-RFP previously digested with BamHI and HindIII. d pGFP-RFP cloning/expression region. One/two consecutive rare codons were introduced into ORF1 of pGFP-RFP after BamHI site, generating pGFPI-RFP/pGFPII-RFP vector