A genetic toolkit for co-expression of multiple proteins of diverse physiological implication

Construction of plasmids is crucial for expression of functional proteins of diverse physiological impact in E. coli. Here, we first designed and constructed a novel pair of bacterial expression vectors, i.e., pAS01 and pAS02, to be co-transformed with pQE30 for the co-expression of three target genes. The three plasmids contain ColE1, p15A and pSC101 origin of replication for high, medium and low copy plasmids, respectively, and same promoter (T5) and RBS. We then cloned genes encoding three reporter proteins (GFPuv, TurboRFP, and EYFP) in each of these plasmids and co-expressed in E. coli in six different combinations. Each of these reporter proteins exhibited diverse impact on growth, plasmid copy number and stability, and expression of other reporter proteins. Our results indicate that GFP and RFP were the most and the least favorable proteins for the cells, respectively, in terms of these parameters, especially on impacting expression of other co-expressed proteins.