Virus Induction of Heat Shock Protein 70 Reflects a General Response to Protein Accumulation in the Plant Cytosol

• Published in: Plant physiology (Bethesda) Vol. 138; no. 1; pp. 529 - 536
• Main Authors: Aparicio, Frederic, Thomas, Carole L, Lederer, Carsten, Niu, Yan, Wang, Daowen, Maule, Andrew J
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-05-2005; American Society of Plant Physiologists
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - virology; Arabidopsis Proteins - biosynthesis; Arabidopsis Proteins - genetics; Arabidopsis thaliana; Base Sequence; Biological and medical sciences; Cell biochemistry; Cell physiology; cytosol; Cytosol - metabolism; DNA Primers; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Viral; Genes; Genes, Reporter; Genetic vectors; heat shock proteins; HSP70 Heat-Shock Proteins - genetics; Infections; Leaves; Nicotiana benthamiana; Open reading frames; plant biochemistry; Plant physiology and development; plant proteins; plant viruses; Plants Interacting with Other Organisms; Potyvirus; Promoter Regions, Genetic; Shock heating; tobacco; Tobacco rattle virus; transgenic plants; Turnip crinkle virus; Turnip mosaic virus; Turnip vein-clearing virus; Viral proteins; Virus replication; Viruses; Arabidopsis thaliana; Gene; Cruciferae; Dicotyledones; Angiospermae; Heat shock protein; Spermatophyta; Plant leaf; Endoplasmic reticulum
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.058958

Different cytoplasmically replicating RNA viruses were shown to induce a specific subset of heat-inducible heat shock protein 70 (HSP70) genes in Arabidopsis (Arabidopsis thaliana). To identify the inducing principle, a promoter::reporter system was developed for the facile analysis of differentially responding Arabidopsis HSP70 genes, by infiltration into Nicotiana benthamiana leaves. Through transient expression of individual viral cistrons or through deletion analysis of a viral replicon, we were unable to identify a unique inducer of HSP70. However, there was a positive correlation between the translatability of the test construct and the differential induction of HSP70. Since these data implied a lack of specificity in the induction process, we also expressed a random series of cytosolically targeted Arabidopsis genes and showed that these also differentially induced HSP70. Through a comparison of different promoter::reporter constructs and through measurements of the steady-state levels of the individual proteins, it appeared that the HSP70 response reflected the ability of the cytosol to sense individual properties of particular proteins when expressed at high levels. This phenomenon is reminiscent of the unfolded protein response observed when the induced accumulation of proteins in the endoplasmic reticulum also induces a specific suite of chaperones.