title: Morphogenesis of bacteriophage phi 29 of Bacillus subtilis: preliminary isolation and characterization of intermediate particles of the assembly pathway.
abstract: Three classes of particles have been identified in restrictive phi 29 suppressor-sensitive (sus) mutant infections of Bacillus subtilis, including DNA-containing heads or phage, prohead, and empty heads. Pulse-chase labeling experiments indicate that the prohead, the first particle assembled in 14-infected cells, is converted to DNA-filled heads and phi 29. In addition to the proteins Hd, P10, and F found in mature phi 29, the prohead contains a "core" protein P7 that exits as the prohead matures and appears to recycle during subsequent rounds of prohead assembly. Prohead-like structures accumulate in UV-irradiated cells and are present in restrictive infections with sus mutants of cistrons 9 and 16. Empty heads are observed only when infection results in the formation of DNA-containing particles; this and other evidence indicates that the empty heads are probably not true intermediates. Phage phi 29 assembly apparently occurs by a single pathway in which neck and tail components interact to stabilize the completed DNA-containing head.
mesh_terms: D001412:Bacillus subtilis; D001435:Bacteriophages / Q000032:analysis / Q000254:growth & development*; D004279:DNA, Viral / Q000032:analysis; D008954:Models, Biological; D009024:Morphogenesis; D009154:Mutation; D013489:Suppression, Genetic; D014466:Ultraviolet Rays; D014764:Viral Proteins / Q000032:analysis; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins