A flexivirus and its interactions with chloroplasts, a step forward (Abstract/Comunicazione in atti di convegno)

Type
Label
  • A flexivirus and its interactions with chloroplasts, a step forward (Abstract/Comunicazione in atti di convegno) (literal)
Anno
  • 2014-01-01T00:00:00+01:00 (literal)
Alternative label
  • Vaira A.M., Lim H-S., Miozzi L., Vallino M., Hammond J. (2014)
    A flexivirus and its interactions with chloroplasts, a step forward
    in 23th Annual Meeting & International Symposium on "Plant Virus Diseases", Pukyong National University, Busan, South Korea, 22nd October 2014
    (literal)
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  • Vaira A.M., Lim H-S., Miozzi L., Vallino M., Hammond J. (literal)
Pagina inizio
  • 9 (literal)
Pagina fine
  • 9 (literal)
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  • organized by the Korean Society for Plant Virology (literal)
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  • 1 (literal)
Note
  • Comunicazione (literal)
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  • Hammond J. - USDA-ARS, USNA, Floral and Nursery Plants Research Unit, MD, USA Lim H.-S. - Department of Applied Biology, Chungnam National University, Daejeon, Republic of Korea (literal)
Titolo
  • A flexivirus and its interactions with chloroplasts, a step forward (literal)
Abstract
  • Flexivirus virions are flexuous filaments, 470 to over 1000 nm in length, and the viral capsid of all species is normally made of a single polypeptide (Adams MJ, 2005); Lolium latent virus (LoLV) is a recently described new flexivirus, for which a new genus, Lolavirus, has been created. LoLV has a unique feature inside flexiviruses: the presence of two carboxy-coterminal coat protein (CP) variants, forming the viral particle, in almost equimolar amount (Vaira et al., 2008). The two CP variants are detected both in infected plant tissue and in purified virus preparations. The open reading frame encoding the LoLV coat protein is 882 nt long, and encodes for a 293 amino acids protein with predicted molecular weight of 31.6 kDa (apparent MW of about 33kDa); a second AUG, in frame with the first is present 141 bases after the first AUG and it is placed in a better translation context (Joshi et al., 1997) (apparent MW of about 28kDa). The 293 aa sequence derived from LoLV CP ORF was checked for prediction of subcellular localization (Emanuelsson et al., 2007). The chloroplast is identified as target for the sequence and a chloroplast transit peptide (cTP) is found at its N terminus. The indicated cTP length is predicted to be 42 aa long, 6 aa before the methionine coded by the second ATG and can potentially lead to proteolytic cleavage of CP at chloroplast sites, being an alternative means of production of the 28kDa CP (Soll and Schleiff, 2004). The cTP sequence is also able to drive localization of marker genes to the chloroplasts in vivo, in the mesophyll layer. Mutational analysis of each of the in-frame CP gene start codons, and of the putative proteolytic cleavage site showed that the N-terminal cTP domain is critical for several key aspects in virus infection: efficient cell-to-cell movement and functional systemic translocation in the plant are not accomplished when the CP N-terminal is absent and only the 28kDa CP is expressed, and virus particle formation is also prevented; but at the same time the sequence is not required for virus replication (Vaira et al., 2012). The cleaved LoLV CP (28kDa) is unequivocally detected inside chloroplasts of infected tissues, associated to the membrane fraction. Interestingly, a yeast-two hybrid experiment using the 33kDa LoLV CP as a bait to screen an A. thaliana cDNA library revealed several CP-host protein interactions related to chloroplast functioning; one of these, an ankyrin repeat-containing protein is being studied in detail: we are analyzing its subcellular localization and we are checking its interaction with LoLV coat proteins in vivo through bimolecular fluorescence complementation (BiFC) (Kerppola and Sullivan, 2008). Results obtained in these experiments will be presented and discussed. (literal)
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