Journal Article

Influence of Host Chloroplast Proteins on Tobacco mosaic virus Accumulation and Intercellular Movement

Cole, Anthony B., Nelson, Richard S., Ballard, Kimberly D., Sumner, Lloyd W., Watson, Bonnie S., Bhat, Sumana, Lei, Zhentian, Folimonova, Svetlana Y.

2013

Overview

Tobacco mosaic virus (TMV) forms dense cytoplasmic bodies containing replication-associated proteins (virus replication complexes [VRCs]) upon infection. To identify host proteins that interact with individual viral components of VRCs or VRCs in toto, we isolated viral replicase-and VRC-enriched fractions from TMV-infected Nicotiana tabacum plants. Two host proteins in enriched fractions, ATP-synthase y-subunit (AtpC) and Rubisco activase (RCA) were identified by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry or liquid chromatography-tandem mass spectrometry. Through pulldown analysis, RCA bound predominantly to the region between the methyltransferase and helicase domains of the TMV replicase. Tobamovirus, but not Cucumber mosaic virus or Potato virus X, infection of N. tabacum plants resulted in 50% reductions in Rea and AtpC messenger RNA levels. To investigate the role of these host proteins in TMV accumulation and plant defense, we used a Tobacco rattle virus vector to silence these genes in Nicotiana benthamiana plants prior to challenge with TMV expressing green fluorescent protein. TMV-induced fluorescent lesions on Rea-or AtpC-silenced leaves were, respectively, similar or twice the size of those on leaves expressing these genes. Silencing Rea and AtpC did not influence the spread of Tomato bushy stunt virus and Potato virus X. In AtpC- and Rca-silenced leaves TMV accumulation and pathogenicity were greatly enhanced, suggesting a role of both host-encoded proteins in a defense response against TMV. In addition, silencing these host genes altered the phenotype of the TMV infection foci and VRCs, yielding foci with concentric fluorescent rings and dramatically more but smaller VRCs. The concentric rings occurred through renewed virus accumulation internal to the infection front.

• Publisher: American Society of Plant Biologists
• Subject: Biological and medical sciences / CELL BIOLOGY / Chloroplast Proteins - genetics / Chloroplast Proteins - metabolism / Chloroplasts / Chloroplasts - metabolism / Chloroplasts - virology / Cucumber mosaic virus / fluorescence / Fundamental and applied biological sciences. Psychology / Gene Silencing / genes / Genetic Vectors - genetics / Genetic Vectors - metabolism / green fluorescent protein / Green Fluorescent Proteins - genetics / Green Fluorescent Proteins - metabolism / Host-Pathogen Interactions / infection / Infections / ionization / Leaves / Lesions / liquid chromatography / Messenger RNA / methyltransferases / Nicotiana - genetics / Nicotiana - metabolism / Nicotiana - virology / Nicotiana benthamiana / Nicotiana tabacum / pathogenicity / Phenotype / Phytopathology. Animal pests. Plant and forest protection / Plant Diseases - virology / plant diseases and disorders / Plant Leaves - genetics / Plant Leaves - metabolism / Plant physiology and development / Plant Proteins - genetics / Plant Proteins - metabolism / plant viruses / Plant viruses and viroids / Plants / Potato virus A / Potato virus X / Potexvirus - metabolism / Potexvirus - pathogenicity / Protein Interaction Mapping / Protein Transport / Proteins / Proteomics - methods / ribulose-bisphosphate carboxylase activase / RNA / RNA, Messenger - genetics / RNA, Messenger - metabolism / RNA-Dependent RNA Polymerase - genetics / RNA-Dependent RNA Polymerase - metabolism / Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods / tandem mass spectrometry / Tobacco mosaic virus / Tobacco Mosaic Virus - enzymology / Tobacco Mosaic Virus - pathogenicity / Tobacco Mosaic Virus - physiology / Tobacco rattle virus / Tomato bushy stunt virus / Tombusvirus - metabolism / Tombusvirus - pathogenicity / Viral Proteins - genetics / Viral Proteins - metabolism / Virus Replication / Viruses