Intracellular fusion expression type pre-T vector, preparation and application

The invention provides a cell fusion expression pre-T vector, which is prepared by the following method: firstly, a DNA1 fragment of BspTI-GSGSG-HHHHHH-XcmI-Amp-XcmI-HindIII is established and encoded; secondly, the DNA sequence of three XcmI sites in an LacI gene in a site-directed mutation pET39 plasmid is changed under the condition that the encoding amino acid sequence is unchanged, so as to lose XcmI recognition sites, and site-directed mutation pET39-1 which eliminates the XcmI sites is obtained; thirdly, DNA1 is directionally recombined into pET39-2 by utilization of BspTI and HindIII; and fourthly, a DsbA signal peptide gene in the pET39-2 is removed, and the cell fusion expression pre-T vector is obtained. Besides the XcmI for preparing a linear T vector, the invention does not need to use other restriction enzymes, can further establish fusion expression genetic engineering bacteria in one step, and provides a feasible technical method for preparing a plurality of bioactive peptide engineering bacte