pADL-pIII-3 Vector

The pADL-pIII-3 vector is a meticulously designed phagemid vector purposed for phage display on the N-terminal side of the M13 filamentous bacteriophage or analogues protein III. One of the salient features is the inclusion of a PelB leader sequence which initiates efficient expression of the vector in the bacterium's periplasm. Additionally, the vector offers convenience in the genetic manipulation with a double-SfiI cloning site, allowing scientists to easily introduce scFvs or Fab fragments needed for variable region cloning. For experimental detection and purification purposes, there is a provision of a HIS tag and a Myc tag respectively. A HIS tag allows for easy protein purification, using nickel-based separation methods, while the Myc tag facilitates the detection process with the antibody. Furthermore, it includes an amber codon (a stop signal for protein synthesis) positioned before the full-length copy of the gene III sequence. Another notable aspect of the pADL-pIII-3 structure is determined by its lac promoter - the expression of protein fusion is under its stringent regulation. This, coupled with a strong transcriptional terminator upstream from the promoter, effectively prevents undesirable gene expression and inhibits promoter leakiness in the absence of induction. This significantly mitigates the danger of negative selection against clones bearing toxic elements.