[Construction of secretion vectors using signal sequence of Bacillus subtilis alkaline protease E gene]

Escherichia coli can be used to study the expression signal of the gene aprE (alkaline protease E) according to its promoter strength to express the promoterless cat-86 gene in a promoter-probe plasmid, pGKV210. We have constructed a signal-sequence-probe plasmid, pBLa, based on the E. coli-B. subtilis plasmid pHP13, using the M. bla as a reporter. Two secretion vectors pSP1 and pSP2 were constructed subsequently based on pHP13 using the promoter and the signal sequence of aprE. DB104 carrying pSP1 showed much higher secretion rate of M. bla than that carrying pSP2. Analysis of DNA sequences surrounding the fusion junctions of the signal sequences and the M. bla gene in the two plasmids indicated that the signal sequence in pSP1 had a 30bp deletion at its 3' end. A new signal peptidase recognition site has been found in the linker-encoded amino acid sequence. The change in length of the signal peptide might somehow increase the secretion efficiency or the synthesis of M. bla.