Notes on Genus: Carmovirus

icosahedra

Type member: Carnation mottle virus

Contents

Members of this Genus
General Description
Morphology
Electron Micrograph
Genome
Genus Genomic Organization
Genome Map
Type Member Genomic Organization
All Known Sequences
Curated Sequences

General Description

The genus Carmovirus (carnation mottle virus group) is one of 11 genera in the family Tombusviridae. All the genera are morphologically similar, with icosahedral particles and small, (usually) monopartite ss RNA genomes. The members of the genus resemble those of the genera Aureusvirus and Tombusvirus in having 5 open reading frames and a large (>35 kDa) coat protein, but their genomes are smaller (<4.4 kb) and the coat protein gene is at the 3'-end of the RNA.

Morphology

Virions isometric (icosahedral; T=3), not enveloped and about 30 nm in diameter. The nucleocapsids have an obvious regular, apparently round, surface structure. 32 capsomeres per nucleocapsid (virion composed of 180 protein subunits).

Virions composed of 17 % nucleic acid.

Genome

Monopartite, linear, single stranded, positive sense RNA of length 4000-4100 nucleotides. The 3' terminus has no poly(A) tract. The 5' terminus probably has a methylated nucleotide cap (the terminus is protected but the presence of a cap has been demonstrated only in carnation mottle virus).

Genus Genomic Organization

For most of the well-studied members, there are five open reading frames, three of which are translated from two subgenomic RNAs:

1. c. 28 kDaPolymerase
2. c. 88 kDaPolymerase readthrough
3. 7-8 kDaMovement protein 1 (cell-to-cell transport, translated from subgenomic RNA 1)
4. 8-9 kDaMovement protein 2 (cell-to-cell transport, translated from subgenomic RNA 1)
5. c. 40 kDaCoat protein, translated from subgenomic RNA2

Type Member Genomic Organization

The RNA is translated into five putative products:

1. 27 kDaPolymerase
2. 88 kDaPolymerase readthrough
3. 7 kDaMovement protein 1 (cell-to-cell transport, translated from subgenomic RNA 1; 1689 nt)
4. 8 kDaMovement protein 2 (cell-to-cell transport, translated from subgenomic RNA1)
5. 38 kDaCoat protein, translated from subgenomic RNA2 (1431 nt)