Induction of apoptosis in Saccharomyces cerevisiae results in the spontaneous maturation of tetravirus procapsids in vivo

• DOI: 10.1099/vir.0.82250-0
• Publication Date: 2007-04-05T19:24:40Z
• Authors: Michele Tomasicchio; Philip Arno Venter; Karl H. J. Gordon; Terry N. Hanzlik; Rosemary Ann Dorr...
• Keywords: Gene Expression Regulation, Viral; 0303 health sciences; 03 medical and health sciences; In Situ Nick-End Labeling; RNA Viruses; Apoptosis; Insect Viruses; Saccharomyces cerevisiae; 3. Good health

TheTetraviridaeare a family of small, non-enveloped, insect RNA viruses consisting of one or two single-stranded, positive-sense genomic RNAs encapsidated in an icosahedral capsid withT=4 symmetry. Tetravirus procapsids undergo maturation when exposed to a low pH environmentin vitro. While the structural biology of the conformational changes that mediate acid-dependent maturation is well understood, little is known about the significance of acid-dependent maturationin vivo. To address this question, the capsid-coding sequence of the tetravirusHelicoverpa armigera stunt viruswas expressed inSaccharomyces cerevisiaecells. Virus-like particles were shown to assemble as procapsids that matured spontaneouslyin vivoas the cells began to age. Growth in the presence of hydrogen peroxide or acetic acid, which induced apoptosis or programmed cell death in the yeast cells, resulted in virus-like particle maturation. The results demonstrate that assembly-dependent maturation of tetravirus procapsidsin vivois linked to the onset of apoptosis in yeast cells. We propose that the reduction in pH required for tetraviral maturation may be the result of cytosolic acidification, which is associated with the early onset of programmed cell death in infected cells.