Studies on the morphopoiesis of the head of phage T-even

To produce polyheads, the normal functions of two “head” genes are necessary: (a) gene 23 which is believed to produce the protein subunit of the capsid, and (b) gene 31, the function of which has not yet been identified.

Abstract

Conditional lethal mutations in gene 20 lead to the production of polyheads. Observed intracellularly in sections, polyheads are tubular structures. The cross sections are frequently pentagonal. Polyheads are filled with an unidentified internal substance which is different—at least in concentration—from the contents of normal phage. In a lysate most polyheads are open, but a few are sealed at one or both ends; most open polyheads appear empty upon examination. Serological studies show that polyheads and normal heads have at least one antigenic site in common. The normal heads have at least one more antigenic site than the polyheads. To produce polyheads, the normal functions of two “head” genes are necessary: (a) gene 23 which is believed to produce the protein subunit of the capsid, and (b) gene 31, the function of which has not yet been identified. A temperature-sensitive mutation L65 in gene 23 produces abnormal phage heads. This abnormality is also observed in polyheads produced by the double mutant tsL65 (in gene 23) -amN50 (in gene 20).