Attachment of tail fibers in bacteriophage T4 assembly: Some properties of the reaction in vitro and its genetic control

Abstract

Purified tail-fiberless T4 particles can be converted to infectious phage in vitro by incubation with a T4-infected-cell extract supplying tail fibers. The kinetics of conversion can be accounted for if it is assumed that fibers are attached randomly and one at a time, and that less than six fibers per particle are required for infectivity. The rate of fiber attachment is temperature dependent. The reaction requires either a divalent or a monovalent cation, as well as a high molecular weight heat-labile factor which can be separated from tail fibers. Attempts to show that the factor is depleted during the attachment reaction have been negative, suggesting that it may act catalytically. Its synthesis is induced early after infection and continues throughout most of the latent period, regardless of whether or not phage DNA synthesis is blocked by mutation. Evidence is presented that the factor is the product of phage gene 63.