Construction of vectors for tight regulation and repression of protein expression

Abstract Introduction Protein expression by means of vector construction may facilitate in the synthesis of protein in sufficient amount for characterization, quorum sensing and molecular diagnostic studies. However, significant amount of protein also can be expressed even under non-inducing and repressed conditions when using many of the vectors available nowadays. In this communication, we report on the design of several genetic elements which resulted in more regulable and thus more tightly repressible protein expression system when grown under repressed conditions. Objective To construct vectors for tight regulation and repression of protein expression. Methods The genetic tools were generated via PCR and inserted into the newly constructed vectors by restriction endonucleases. Analysis of the constructed vectors was carried out by restriction endonuclease digestion and DNA sequencing. Elastase, on the other hand, was used as a model protein to test on the efficiency of the constructs. Thus, the resulting protein expression level was determined using elastinolytic assay (Ohman et al ., 1980). Results & Discussion The constructs harboring a PT7 -dual operator system have greatly regulated and reduced the level of basal protein expression. In addition, the presence of a repressor gene has further assisted in controlling the expression level upon induction in several heterogeneous host systems. Conclusion The ‘tightness' and repression effects of the genetic elements in these constructs have lent remarkable support in expression of foreign genes in bacterial host systems.