title: Q beta-defective particles produced in a streptomycin-resistant Escherichia coli mutant.
abstract: This paper describes Q beta noninfectious particles produced at 41 degrees C in a streptomycin-resistant Escherichia coli mutant which is temperature sensitive for suppression of a nonsense codon. The noninfectious particles resembled Q beta under the electron microscope and contained coat protein molecules in an amount similar to the amount in Q beta. However, they did not adsorb to F-piliated bacteria, and they were deficient in both minor capsid proteins of Q beta, maturation (IIa) and read-through (IIb). Proteins IIa and IIb were not produced in Qbeta-infected mutant cells at 41 degrees C. In addition, instead of the 30S RNA of Q beta, a shorter RNA, which sedimented mainly at 23 S, was found in the defective particles. The results are discussed in relation to the roles of proteins IIa and IIb of Q beta.
mesh_terms: D000327:Adsorption; D003090:Coliphages / Q000254:growth & development* / Q000648:ultrastructure; D003673:Defective Viruses / Q000254:growth & development* / Q000648:ultrastructure; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D012367:RNA, Viral / Q000032:analysis; D013307:Streptomycin / Q000494:pharmacology; D013696:Temperature; D014764:Viral Proteins / Q000032:analysis; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D013307:Streptomycin