title: Bacterial rep- mutations that block development of small DNA bacteriophages late in infection.
abstract: Several related mutants of Escherichia coli C have been isolated that block the growth of the small icosahedral DNA phages phiX174 and S13 late in infection. Phage G6 is also blocked, at a stage not yet known. Growth of the filamentous phage M13, though not blocked, is affected in these strains. These host mutations co-transduce with ilv at high frequency, as do rep- mutations. However, the new mutants, designated groL-, differ from previously studied rep- mutants in that they permit synthesis of progeny replicative-form DNA. The groL- mutants are blocked in synthesis of stable single-stranded DNA of phiX174 and related phages. They are gro+ for P2. Evidence that groL- mutations and rep- mutations are in the same gene is presented. Spontaneous mutants (ogr) of phiX174, S13, and the G phages can grow on groL- strains. The ogr mutations are located in the phage's major capsid gene, F, as determined by complementation tests. There are numerous sites for mutation to ogr. Some mutations in genes A and F interfere with the ogr property when combined with an ogr mutation on the same genome. The ogr mutations are cis acting in a groL- cell; i.e., an ogr mutant gives very poor rescue of a non-ogr mutant. The wild-type form of each G phage appears to be naturally in the ogr mutant state for one or more groL- strains. It is suggested that a complex between F and rep proteins is involved in phage maturation. The A protein appears to interact with this complex.
mesh_terms: D002701:Chloramphenicol / Q000494:pharmacology; D003090:Coliphages / Q000254:growth & development* / Q000378:metabolism; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis; D004926:Escherichia coli / Q000378:metabolism; D005799:Genes, Dominant; D009154:Mutation; D011995:Recombination, Genetic; D013696:Temperature; D014161:Transduction, Genetic; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D002701:Chloramphenicol