Element:FMV

From The Gypsy Database

Description

Figwort mosaic virus (FMV) is a plant pararetrovirus belonging to the genus Caulimovirus of Caulimoviridae family (International Committee on the Taxonomy of Viruses -ICTV- Fauquet et al. 2005). Although its original host was the flowering plant Scrophularia californica (Scrophulariaceae family), it is also able to infect solanaceous plants (Rollo et al. 1986; Richins et al. 1987).

FMV isometric virions are composed of a genomic circular double-stranded DNA of 7743 bp containing four discontinuities, one in the (-) strand and three in the complementary strand. The genome is organized into seven major open reading frames (ORFs) whose size and organization are similar to those of known caulimoviruses (Richins et al. 1987). ORF I encodes a protein of 327 amino acids (aa) associated to cell-to-cell movement (MOV); the ORF II (164 aa) and ORF III (115 aa) predicted products showing sequence similarities with the "aphid transmission factor" (ATF) and "virion associated protein" (VAP), respectively. ORF IV encodes the putative COAT protein and contains the "RNA-binding" motif characteristic of the Caulimoviridae Gag-like domain (C-X-C-X2-C-X4-H-X4-C ) (Bouhida et al. 1993; Hull 1996; Llorens et al 2009). ORF V product is a polyprotein of 666 aa displaying the typical Pol domains -aspartic protease (PR), reverse transcriptase (RT) and RNase H (RH)- while the ORF VI-encoded product of 512 aa is similar to the caulimoviruses-related "Translational transactivator proteins" (TAVs). The small ORF VII immediately precedes ORF I and encodes a 7.4 kDa protein which function is still unknown (Richins et al. 1987). Like other Caulimovirus species (CERV, CaMV, EVCV, LLDAV), two intergenic regions are also present in the genome of FMV: a large intergenic region (LIR) located between ORFs VI (TAV) and VII, and a small intergenic region (SIR) located between ORFs V (Pol) and VI. These regions contain two transcriptional promoter sequences that transcribe whole genome of the virus (that within the LIR) or only the ORF VI (that within the SIR) (Sanger et al. 1990; Bhattacharyya et al. 2002).

Structure

FMV.png


Figure not to scale. If present, long terminal repeats (LTRs) have been highlighted in blue. Amino acid motifs noted with lines indicate the conserved residues in each protein domain, abbreviations below mean:

MA=matrix PR=protease DU or DUT=dUTPase TM=transmembrane TAV or IBMP=transactivator/viroplasmin or inclusion body matrix protein
CA=capsid RT=reverse transcriptase INT=Integrase CHR=chromodomain
NC=nucleocapsid RH=RNaseH SU=surface MOV=movement protein
PPT=polypurine tract PBS=primer binding site ATF=aphid transmission factor VAP=virion associated protein

Related literature

Genbank accession:20143424
Clade:'
Cluster or genus:Caulimovirus
Branch or class:Class 1
Family:Caulimoviridae
System:LTR retroelements
Host:
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Scrophularia californica.jpg
Scrophularia californica
Courtesy of Wikipedia, copyright of the authors Gordon Leppig & Andrea J. Pickart
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