ABSTRACT
The deoxyribonucleic acid (DNA)-containing, protein capsid of all well-studied, double-stranded DNA phages begins its existence as a DNA-free capsid, called a procapsid. The phage particle consists of a DNA-encapsulating shell of the protein product of gene 10, called gp10; an external structure (tail) adapted for specific binding to host cells and an internal core stack. Pathogenic viruses do make extensive a-sheet-containing shell intermediates, at least in the case of the capsids of viruses with a double-stranded DNA genome, such as herpes viruses. The DNA remaining packaged is obtained by DNase I-digestion of external DNA; and expulsion from the capsid of DNA remaining package. In the shell-revealing regions of hyper-expanded ipDNA-capsid II particles, the shell usually appears 3–5 nm thick. The connector of phages T3 and T7 also exists for all other studied double-stranded DNA phages. Less direct evidence for shell dynamics arises from analysis of the leakage of DNA from phage T3 heads.
