title: Heterologous expression of a gene of Magnaporthe oryzae chrysovirus 1 strain A disrupts growth of the human pathogenic fungus Cryptococcus neoformans.
abstract: Magnaporthe oryzae chrysovirus 1 strain A (MoCV1-A) is the causal agent of growth repression and attenuated virulence (hypovirulence) of the rice blast fungus, M. oryzae. We have previously reported that heterologous expression of MoCV1-A ORF4 in Saccharomyces cerevisiae results in growth defects, a large central vacuole and other cytological changes. In this study, the effects of open reading frame (ORF) 4 expression in Cryptococcus neoformans, a human pathogenic fungus responsible for severe opportunistic infection, were investigated. Cells expressing the ORF4 gene in C. neoformans showed remarkably enlarged vacuoles, nuclear diffusion and a reduced growth rate. In addition, expression of ORF4 apparently suppressed formation of the capsule that surrounds the entire cell wall, which is one of the most important components of expression of virulence. After 5-fluoroorotic acid treatment of ORF4-expressing cells to remove the plasmid carrying the ORF4 gene, the resultant plasmid-free cells recovered normal morphology and growth, indicating that heterologous expression of the MoCV1-A ORF4 gene induces negative effects in C. neoformans. These data suggest that the ORF4 product is a candidate for a pharmaceutical protein to control disease caused by C. neoformans.
authors.affiliation: Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509.
authors.forename: Syun-Ichi
authors.initials: S
authors.lastname: Urayama
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fukuhara
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Moriyama
authors.forename: Akio
authors.initials: A
authors.lastname: Toh-E
authors.forename: Susumu
authors.initials: S
authors.lastname: Kawamoto
mesh_terms: D003455:Cryptococcus neoformans / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D005814:Genes, Viral; D020082:Magnaporthe / Q000821:virology*; D015388:Organelles / Q000648:ultrastructure; D012328:RNA Viruses / Q000235:genetics* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000633:toxicity*
chemical_list: D011994:Recombinant Proteins
keywords: Cryptococcus neoformans; capsule formation; heterologous expression; mycovirus