CLONING VECTOR COMPRISING A SYSTEM FOR DIRECT SELECTION OF RECOMBINANTS

摘要

The present invention relates to a modified cloning vector comprising a system that can be used for the direct selection of recombinants through the activation of antibiotic resistance gene. A fragment of the lacl gene involved in this system has been modified to introduce a multiple cloning site (MCS) region. According to this invention, at least one antibiotic resistance marker is linked to and is under the control of a promoter that is regulated by a lacl gene product. This structure is defined as the lac-ABR operon which consists of the lac promoter, the lacl-regulated operator and an antibiotic resistance marker coding sequence. Additionally, the vector contains a promoter named DELTA TAC that is derived from modification of the TAC promoter and is linked to the lacl gene. With this promoter, the lacl gene can be expressed permanently at a high level. Any DNA can be introduced into the MCS region of the lacl DNA sequence by ligation to any restriction enzyme site within the MCS sequence.