Peripheral association of a polyprotein precursor form of the RNA-dependent RNA polymerase of Tomato ringspot virus with the membrane-bound viral replication complex.
Replication of Tomato ringspot virus (ToRSV) occurs in association with endoplasmic reticulum (ER)-derived membranes. We have previously shown that the putative nucleotide triphosphate-binding protein (NTB) of ToRSV is an ER-targeted protein and that an intermediate polyprotein containing the domains for NTB and for the genome-linked viral protein (VPg) is associated with the replication complex. We now report the detection of a 95-kDa polyprotein that contains the domains for the RNA-dependent RNA polymerase (Pol), the proteinase (Pro) and the VPg. This polyprotein appears to be a truncated version of the full-length 111-kDa VPg-Pro-Pol polyprotein and was termed VPg-Pro-Pol'. A subpopulation of VPg-Pro-Pol' was peripherally associated with ER-derived membranes active in viral replication. However, the VPg, Pro and Pol domains did not target to membranes in the absence of viral infection. We propose a model in which VPg-Pro-Pol' is brought to the site of replication through interaction with a viral membrane protein.
Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, P.O. Box 5000, 4200 Highway 97, Summerland, B.C., Canada V0H 1Z0.
Joan
J
Chisholm
Guangzhi
G
Zhang
Aiming
A
Wang
Hélène
H
Sanfaçon
D000595:Amino Acid Sequence; D018553:Cucumis sativus / Q000821:virology*; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000821:virology; D015684:Gene Products, pol / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry; D008969:Molecular Sequence Data; D017860:Nepovirus / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D020815:Polyproteins / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D016415:Sequence Alignment; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication
D015684:Gene Products, pol; D020815:Polyproteins; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase; D010447:Peptide Hydrolases