Binding, eclipse, and penetration of the filamentous bacteriophage M13 in intact and disrupted cells

Abstract

Interaction between the filamentous phage M13 and the Escherichia coli host progresses through stages of binding, eclipse, and penetration, defined as follows: binding of phage to cell receptor may be reversible or irreversible, eclipse of phage makes it noninfective and susceptible to DNase, and penetration entails uptake of phage components in a manner tightly coupled to replication. Binding (or adsorption) was specific for F + cells, was relatively slow, did not follow simple bimolecular kinetics, and attained a value of about one phage per cell. It was blocked by low temperature, cyanide, or starvation and was unaffected by rifampicin. Binding capacity of phages was removed by subtilisin treatment which also released the gene 3 (adsorption) protein from the viral particle. Rifampicin which blocks replication prevents penetration of an irreversibly attached and altered (“eclipsed”) phage. Thus, decapsidation and penetration of the phage are coupled to replication of the viral DNA. Binding or eclipse triggered an alteration of the gene 3 protein to a lower molecular-weight form. The coat proteins (gene 3 and gene 8) were taken up by the cells to the same extent as the DNA. Cells disrupted by lysozyme-detergent treatment, as judged by release of β-galactosidase, retained their capacity to bind and eclipse the phage particle; binding to disrupted cells remained cyanide sensitive. After this treatment F − cells were as active in the binding of M13 as F + cells. Such preparations from both F + and F − cells had the capacity of replicating the DNA in intact phage particles to the duplex replicative form. In a discussion of these findings, current models for the key role of the F pilus (of F + cells) in phage adsorption are discussed and a larger role for the phage adsorption protein is proposed.