The Protein Coats or "Ghosts" of Coliphage T2

Abstract

With the discovery (1) that the protein coat or "ghost" of coli bacteriophage T2 carried some of the biological functions of the parent virus, it was possible to examine more carefully than heretofore the relationship of biological function to morphological structure and chemical constitution. In the series of papers to follow data will be given to support the statements in the original report (1) and to demonstrate that many properties usually associated with the intact virus are found in the protein component, suggesting a high degree of specialization and organization in this relatively small biological unit.In this, the first, paper will be described the preparation, fractionation, method of assay, and some physicochemical properties of the ghosts of T2 phage. The biological properties of the ghosts will be described in the second paper while studies of the metabolic changes induced in the host cell by ghosts (2, 3) will appear in the third and fourth papers. The inhibitory effect of divalent cations (4) on the action of ghosts will be presented in the fifth paper of this series.In the interim since the first report a number of papers (5-14) have dealt to a varying degree with some of the properties of ghosts. These will be discussed in the text of this and succeeding papers. Materials and MethodsMany of the materials and methods used in the present work are the usual ones (15, 16) described for the T phages of Escherichia coli B. The details are found either in the protocols or in the section on Experimental Details near the end of this paper.Only highly purified phage (titer/E40o > 2) (17) was used in the present experiments. In most instances freshly shocked but unfractionated ghosts were used but in certain critical experiments the results were confirmed with ghosts freed of nucleic acid as described in Table I. These instances are noted in the protocols.

Experimental Differential Light-Scattering Correction to the Circular Dichroism of Bacteriophage T2

“…Although the disrupted T2 samples contain essentially intact phage coats after the DNA is released (46) (42). ticulateness of the specimen rather than the organization of the particle.…”

The Protein Coats or "Ghosts" of Coliphage T2

“…(4) There is, in addition to the phosphorus released in the first 5 minutes, a rapid extracellular accumulation of small molecular organic phosphates. (5) There is no detectable loss of nucleic acid phosphorus from the system, although a small but significant TCAinsoluble phosphorus fraction does accumulate in the medium. This could stem from a few lysed cells or represent the release noted in phage-infected cells (24,12,13).…”

“…Ghosts.--T2 phage was concentrated to approximately 2 × 10 ~ plaque-forming units per ml. and subjected to the osmotic shock method (5). The ghost suspension containing about 1 per cent of the original infectivity was then purified as follows:-…”

“…Measurements of ultraviolet absorption were made in the Beckman model DU spectrophotometer using 1 cm. silica cells and standardized as noted elsewhere (5).…”

“…L = fraction of cells lysed. It was assumed that the drop in turbidity observed in the case of ghost-infected organisms represented lysis of the cells(5) and lysed cells are incapable of respiring. Experiments performed in connection with other work lend substantial support to this assumption(22).…”