title: Capsid size and deoxyribonucleic acid length: the petite variant of bacteriophage T4.
abstract: A mutant which produces a small-headed ("petite") variant of bacteriophage T4 is described. The mutation (E920g) maps in a new gene (66) between genes 23 and 24. Petite phage particles composed up to 70% of the phage yield. The petite phage was nonviable upon single infection but produced progeny when two or more infected a cell. Its genome was shortened by a random deletion of about 30%, and deoxyribonucleic acid (DNA) extracted from the particles was 0.68 the length of normal T4 DNA. The reduction in DNA length was accompanied by a proportional reduction in head volume. Double mutants between E920g and head-defective mutants in gene 21 produced unusually high frequencies of spherical capsidlike structures (tau-particles).
mesh_terms: D002499:Centrifugation, Density Gradient; D002874:Chromosome Mapping; D003090:Coliphages / Q000032:analysis* / Q000254:growth & development / Q000302:isolation & purification; D003433:Crosses, Genetic; D004279:DNA, Viral / Q000032:analysis; D004926:Escherichia coli; D005796:Genes; D005816:Genetic Complementation Test; D014644:Genetic Variation; D005827:Genetics, Microbial; D008854:Microscopy, Electron; D009154:Mutation; D013395:Sucrose; D014764:Viral Proteins
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D013395:Sucrose