Totivirus
Encyclopedia
The genus Totivirus is a member of the Totiviridae
family. These are a family of icosahedral
nonenveloped viruses. The double-stranded RNA (dsRNA) genomes are packaged in isometric particles 40 to 50 nm in diameter.
of 4700-6700 nucleotides in length and only a single copy of the genome is present in the particle. The nucleic acid
content of Totivirus is usually of one molecule
but can also contain three or four segments of linear double stranded RNA. The genome
contains two large overlapping open reading frame
s (ORFs). These open reading frames (ORFs) code for a capsid protein (CP) and an RNA-dependent RNA polymerase
(RDRP). The 5' end of the positive strand of the dsRNA genome has no cap and is very structured.Totivirus contains a long 5' untranslated region (5' UTR) which functions as an internal ribosome entry site
(IRES).
Totiviruses can have satellite RNAs that encoding a toxin
.
Saccharomyces cerevisiae
. The Helminthosporium victoriae 190S virus which was initially included in this genus has been moved to a new genus - the Victorivirus.
Totiviridae
The Totiviridae are a family of viruses. They are non enveloped, icosahedral viruses. The viron is composed of a single capsid protein and are ~40 nanometers in diameter. The capsid has a T=2 symmetry....
family. These are a family of icosahedral
Icosahedron
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is one of the five Platonic solids....
nonenveloped viruses. The double-stranded RNA (dsRNA) genomes are packaged in isometric particles 40 to 50 nm in diameter.
Genome
Totivirus have a genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of 4700-6700 nucleotides in length and only a single copy of the genome is present in the particle. The nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
content of Totivirus is usually of one molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
but can also contain three or four segments of linear double stranded RNA. The genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
contains two large overlapping open reading frame
Open reading frame
In molecular genetics, an open reading frame is a DNA sequence that does not contain a stop codon in a given reading frame.Normally, inserts which interrupt the reading frame of a subsequent region after the start codon cause frameshift mutation of the sequence and dislocate the sequences for stop...
s (ORFs). These open reading frames (ORFs) code for a capsid protein (CP) and an RNA-dependent RNA polymerase
RNA polymerase
RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...
(RDRP). The 5' end of the positive strand of the dsRNA genome has no cap and is very structured.Totivirus contains a long 5' untranslated region (5' UTR) which functions as an internal ribosome entry site
Internal ribosome entry site
An internal ribosome entry site, abbreviated IRES, is a nucleotide sequence that allows for translation initiation in the middle of a messenger RNA sequence as part of the greater process of protein synthesis...
(IRES).
Totiviruses can have satellite RNAs that encoding a toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
.
Species
One species infects the fungusFungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
. The Helminthosporium victoriae 190S virus which was initially included in this genus has been moved to a new genus - the Victorivirus.