In vitro assembly of the Bacillus subtilis bacteriophage phi 29.

Abstract
In vitro assembly of the B. subtilis bacteriophage .vphi.29 that approaches the efficiency of assembly in vivo was demonstrated. Proheads, DNA and gene 16 product (gp16) were essential for DNA encapsidation and the average yield in extracts was 180 phage/prohead donor cell. The in vitro maturation was very similar to in vivo assembly in terms of yield, intermediates and abortive structures. More than 30% of the proheads in the extract were converted to phage and .apprx. 20% of DNA-protein extracted from phage could be repackaged. In vitro assembly was blocked by the addition of DNase I, EDTA, pyrophosphatase or the ATP analogs adenosine 5''-[.alpha.,.beta.-methylene]triphosphate and adenosine 5''-[.beta.,.gamma.-methylene]triphosphate. Less than 1% of the proheads isolated in sucrose gradients can accept DNA-protein in packaging in vitro.