Screening of Functional Promoter from Metagenomic DNA for Practical Use in Expression Systems

The functional overproduction of proteins is an essential step required for providing enzymes and proteins for practical applications. Accordingly, the expression system used is important, e.g., cis -acting elements including promoters for the expression of recombinant proteins in a broad range of hosts or preferential expression in a specific host. We have introduced a bidirectional promoter trap system (pBGR1) for screening of promoters with up- or/and down regulatory elements from resources of metagenomic DNA. The pBGR1 is equipped with a pair of fluorescent proteins acting as reporters, facing opposite directions without promoters; this is a promising system that can function regardless of the direction of inserted promoters. Subsequently, promoters trapped by pBGR1 can be employed in the construction of new expression vectors for practical applications.