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This Article Full Text Full Text (PDF) All Versions of this Article: vir.0.013862-0v1 90/12/3022    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Makarov, V. V. Articles by Kalinina, N. O. PubMed PubMed Citation Articles by Makarov, V. V. Articles by Kalinina, N. O. Agricola Articles by Makarov, V. V. Articles by Kalinina, N. O.

Domain organization of the N-terminal portion of hordeivirus movement protein TGBp1

Valentin V. Makarov^1,

Ekaterina N. Rybakova^1,

¹ A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
² Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
³ Institute of Physico-Chemical Medicine, Moscow 119828, Russia
⁴ Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Moscow 127550, Russia
⁵ Physical Faculty, Moscow State University, Moscow 119992, Russia
⁶ Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK
⁷ Department of Virology, Biological Faculty, Moscow State University, Moscow 119992, Russia

Correspondence
Natalia Kalinina
kalinina{at}genebee.msu.ru

Three ‘triple gene block’ proteins known as TGBp1, TGBp2 and TGBp3 are required for cell-to-cell movement of plant viruses belonging to a number of genera including Hordeivirus. Hordeiviral TGBp1 interacts with viral genomic RNAs to form ribonucleoprotein (RNP) complexes competent for translocation between cells through plasmodesmata and over long distances via the phloem. Binding of hordeivirus TGBp1 to RNA involves two protein regions, the C-terminal NTPase/helicase domain and the N-terminal extension region. This study demonstrated that the extension region of hordeivirus TGBp1 consists of two structurally and functionally distinct domains called the N-terminal domain (NTD) and the internal domain (ID). In agreement with secondary structure predictions, analysis of circular dichroism spectra of the isolated NTD and ID demonstrated that the NTD represents a natively unfolded protein domain, whereas the ID has a pronounced secondary structure. Both the NTD and ID were able to bind ssRNA non-specifically. However, whilst the NTD interacted with ssRNA non-cooperatively, the ID bound ssRNA in a cooperative manner. Additionally, both domains bound dsRNA. The NTD and ID formed low-molecular-mass oligomers, whereas the ID also gave rise to high-molecular-mass complexes. The isolated ID was able to interact with both the NTD and the C-terminal NTPase/helicase domain in solution. These data demonstrate that the hordeivirus TGBp1 has three RNA-binding domains and that interaction between these structural units can provide a basis for remodelling of viral RNP complexes at different steps of cell-to-cell and long-distance transport of virus infection.

These authors contributed equally to this work.