Notes on Genus: Poacevirus

flexuous filaments

Type member: Triticum mosaic 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

This is one of the genera in the family Potyviridae. Like the other genera, it is characterised by its flexuous filamentous particles, inclusion bodies in infected plant cells and by having a polyprotein genome strategy. It differs from most of the others in having mite transmission and from the genus Bymovirus in having a monopartite genome. The viruses in this genus are phylogenetically very distant from those of other mite-transmitted members in the genera Rymovirus and Tritimovirus. Their genomes also have a very much longer 5'-UTR (>700 nt). The genus name is derived from Poaceae, the family name of the host plants.

Morphology

Virions filamentous, not enveloped, usually flexuous, 680-750 nm long and 12-15 nm in diameter. Symmetry helical with a pitch of 3.4 nm

Virions composed of 5 % nucleic acid and 95 % protein.

Genome

Monopartite, linear, single stranded, positive sense RNA, 9700-10300 nucleotides long. The 3' terminus has a poly(A) tract and the 5' terminus has a genome-linked protein (VPg).

Genus Genomic Organization

Genome organisation appears to be uniform throughout this genus and is similar to other members of the family. The genome is translated into a single polyprotein, which is subsequently processed into ten products, with the coat protein at the C-terminus. An additional small ORF (PIPO) is generated by frameshifting within the third (P3) cistron.

Type Member Genomic Organization

The genome is translated into a single polyprotein of 353 kDa, from which an estimated ten functional products are produced by proteolytic processing:
P1 protein     putative protease    45 kDa
HC-Pro putative helper component protease     53 kDa
P3 protein unknown function     33 kDa
6K1 unknown function    6 kDa
CI Cylindrical inclusion putative helicase     73 kDa
6K2 unknown function     6 kDa
VPg Genome-linked protein     23 kDa
NIa-Pro Nuclear Inclusion putative protease     26 kDa
NIb Nuclear Inclusion putative polymerase     56 kDa
CP coat protein     32 kDa