title: Improved in vitro packaging of coliphage lambda DNA: a one-strain system free from endogenous phage.
abstract: In previous systems for in vitro packaging of lambda DNA, phages are produced from the packaging components as well as from added DNA. We have developed a new genetic strategy for in vitro packaging that bypasses this endogenous phage problem. Our system employs a single bacterial strain whose lambda prophage codes for all of the packaging proteins but is deleted for cos, the packaging origin. Crude extracts of the single lysogen: (i) are virtually free from endogenous phages, (ii) package added lambda DNA efficiently and (iii) are easy to prepare. Using the cos- in vitro packaging system we show that packaging of lambda linear monomers is a second-order reaction, but that packaging from concatemers prepared by annealing or ligation is first order. We conclude that in our cos- system, linear monomers are a poor substrate for in vitro packaging but that packaging from concatemers works well.
authors.forename: S M
authors.initials: SM
authors.lastname: Rosenberg
authors.forename: M M
authors.initials: MM
authors.lastname: Stahl
authors.forename: I
authors.initials: I
authors.lastname: Kobayashi
authors.forename: F W
authors.initials: FW
authors.lastname: Stahl
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics* / Q000648:ultrastructure; D004279:DNA, Viral / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D008242:Lysogeny; D008970:Molecular Weight; D009024:Morphogenesis; D011995:Recombination, Genetic; D014779:Virus Replication
chemical_list: D004279:DNA, Viral