title: Intact ribonucleic acid from defective particles of bacteriophage R17.
abstract: The growth of one group of amber mutants of R17 (class A) in non-permissive hosts results in a burst of bacteriophage-like particles, which are defective in that they are non-infectious. Here studies of particles produced by the growth of wild-type R17 and four class A mutants on AB301, a non-permissive Hfr Escherichia coli strain, and on RNase(-)10, an RNase I-deficient derivative of AB301, are described. Defective particles grown on AB301 contain degraded, non-infectious RNA and are on the average less dense than wild-type phage; particles grown on RNase(-)10 contain intact, infectious RNA and exhibit normal density in cesium chloride gradients, but are nonetheless non-infectious as phage. In addition, the RNA in purified defective particles grown on RNase(-)10 is partially susceptible to nuclease attack, whereas RNA in wild-type phage is not. The studies demonstrate that the presence of degraded RNA in defective particles of R17 results from the action of RNase I during the purification of the particles. The possible function of the A protein of R17 is considered in the light of the results obtained.
authors.affiliation: Biological Laboratories, Harvard University Cambridge, Massachusetts, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Argetsinger
authors.forename: G N
authors.initials: GN
authors.lastname: Gussin
mesh_terms: D018389:Codon, Nonsense / Q000235:genetics / Q000378:metabolism; D003090:Coliphages / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000821:virology*; D020871:RNA Stability; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D018389:Codon, Nonsense; D012367:RNA, Viral; D004722:Endoribonucleases; C022543:ribonuclease T(2)