title: Ultrastructural localization and epitope mapping of the methyltransferase-like and helicase-like proteins of Beet yellows virus.
abstract: Monoclonal antibodies (MAbs) specific to the methyltransferase (MT) and helicase (HEL) domains of the closterovirus Beet yellows virus (BYV) were used for immunogold labelling of ultrathin sections of virus-infected Tetragonia expansa plants. MAbs 4A2 and 4A5 from the MT panel, and 1C4 from the HEL panel, specifically labelled distinct closterovirus-induced membranous structures, the 'BYV-type vesicles', thus suggesting that the closterovirus MT-like and HEL-like proteins co-localize in these structures. Probing of the MT and HEL MAbs with synthetic octapeptides spanning the sequences of the recombinant MT and HEL fragments that had been used as immunogens showed that 4A5 and 4A2 recognized a single epitope, SRLLENET (aa 686-692 in the BYV 1a protein), and 1C4 reacted with the DDPF epitope (aa 2493-2496). These epitopes apparently reside on the exposed parts of the membrane-associated molecules of the closterovirus MT-like and HEL-like proteins. Two other epitopes determined for the MT MAbs that were nonreactive in the immunogold labelling, namely TMVTPGEL (aa 750-757; MAbs 3C5, 4B4 and 4C5) and SREQLVEA (aa 806-813; MAb 2A4), are possibly buried in the MT domain fold or shielded by membranes or other proteins involved in the viral replicative complex.
authors.affiliation: Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, 117871 Moscow, Russia1.
authors.forename: Tatyana N
authors.initials: TN
authors.lastname: Erokhina
authors.affiliation: Department of Virology and Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia2.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Vitushkina
authors.affiliation: Department of Virology and Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia2.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Zinovkin
authors.affiliation: Department of Plant Virology, Microbiology and Biosafety, Federal Biological Research Centre for Agriculture and Forestry, Messeweg 11-12, D-38104 Braunschweig, Germany3.
authors.forename: Dietrich E
authors.initials: DE
authors.lastname: Lesemann
authors.affiliation: Institute for Plant Protection in Fruit Crops, Schwabenheimer Str. 101, D-69221 Dossenheim, Germany4.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Jelkmann
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA5.
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.affiliation: Department of Virology and Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia2.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Agranovsky
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D001665:Binding Sites; D002462:Cell Membrane / Q000821:virology; D017790:Closterovirus / Q000201:enzymology*; D022162:Cytoplasmic Vesicles / Q000821:virology; D000939:Epitopes / Q000276:immunology / Q000302:isolation & purification; D007150:Immunohistochemistry; D008780:Methyltransferases / Q000276:immunology / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000821:virology; D010944:Plants / Q000648:ultrastructure / Q000821:virology*; D020365:RNA Helicases / Q000276:immunology / Q000302:isolation & purification*; D016415:Sequence Alignment
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D008780:Methyltransferases; D020365:RNA Helicases