On the mycophage of Penicillium chrysogenum

Abstract

A mycovirus has been purified from mycelia of Penicillium chrysogenum by isopycnic centrifugation in sucrose and in CsCl. Viral particles band with a buoyant density of 1.20 in sucrose and 1.38 in CsCl. Particles have icosohedral symmetry, are 35 nm in diameter, and have an absorption profile characteristic of nucleoprotein. One enzymatic activity, RNA polymerase, is associated with the purified mycophage. Nucleic acid extracted from purified virus has a buoyant density in CS2SO4 of 1.61, a molar extinction coefficient of εp (258 nm) of 7200, a s20, w of 13.0, and a pattern of circular dichroism characteristic of double-helical ribonucleic acid. Molecules of this double-stranded ribonucleic acid (dsRNA), examined by electron microscopy, have a mean contour length of 0.86 μm which corresponds to a molecular weight of about 2.0 × 106 daltons. This dsRNA is resolved further by acrylamide gel electrophoresis into three closely spaced bands. Thermal denaturation of the viral dsRNA is dependent on ionic strength and gives a linear relationship with the negative logarithm of the sodium ion concentration.

Ribonucleic Acid Synthesis by Isolated Viruses of Penicillium stoloniferum

“…The PsV-F activity differs from that of Penicillium chrysogenum virus (Nash et aL 1973) in being dithiothreitol-independent and in its failure to be stimulated by Triton X-Ioo. The radioactive RNA synthesized in our reaction mixtures is not released from the virus particles, and most of it is double-stranded and, for PsV-F, coelectrophoreses with the various RNA species extracted from purified virus.…”

“…Viruses have been isolated from a wide range of fungi, and all of those studied in detail have turned out to consist of several density components and to contain several species of double-stranded RNA (Wood, 1973)-In the two published cases where it has been sought, evidence of a fungal virus-associated RNA-dependent RNA polymerase has been found; Nash et al (1973) reported a Mg ++-, dithiothreitol-and KCl-dependent RNA polymerase activity associated with Penicillium chrysogenum virus, and Lapierre, Astier-Manifacier & Cornuet (197I) described a Mg++-dependent, ethidium bromide-sensitive activity in P. stoloniferum virus (PsV); the product of this polymerase was partially resistant to pancreatic ribonuclease action.…”

Mycoviruses: A New Dimension in Microbiology

“…Three classes of ds-RNA are also suggested from the data of Buck et al (43), Nash et al (45), and Cox et al (47,48 (23,43,45).…”

“…Others have reported a particle diameter of 35 nm (42,43,45). A molecular weight of 13 x 106 daltons was computed from sedimentation and diffusion data (23).…”

Inhibition of Cellular Protein Synthesis by Double-Stranded RNA: Inactivation of an Initiation Factor

“…Virions associated with the fungus, Penicillium chrysogenum, contain dsRNA (8,9). The potent inhibitory activity of this dsRNA, used in all our experiments, is illustrated in Fig.…”