Polycos vectors: a system for packaging filamentous phage and phagemid vectors using lambda phage packaging extracts

Abstract

A new class of hybrid vectors, ‘polycos’ vectors, incorporate a phage λ cos site and filamentous phage origin to allow high-efficiency cloning via in vitro λ packaging extracts. The head-filling mechanism of cos site recognition by λ packaging proteins permits concatemers of several of these small cos-containing vectors to be packaged per phage particle. Excision of vector monomers after infection is accomplished via a λZAP-like M13 excision process. This system has the advantage of adapting high-efficiency λ packaging extracts to M13 and phagemid cloning vectors.