23-kDa light-stress-regulated heat-shock protein of Chenopodium rubrum L. is located in the mitochondria

• Published in: Planta Vol. 201; no. 3; pp. 326 - 333
• Main Authors: Debel, K, Sierralta, W.D, Braun, H.P, Schmitz, U.K, Kloppstech, K
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01.03.1997; Springer; Springer Nature B.V
• Subjects: Amino Acid Sequence; amino acid sequences; Antibodies; Biological and medical sciences; Cell culture techniques; Cell Fractionation; Cell Nucleus - metabolism; Cells, Cultured; Chenopodium rubrum; Chloroplasts; Drosophila Proteins; Fundamental and applied biological sciences. Psychology; Heat; Heat shock proteins; heat stress; Heat-Shock Proteins - analysis; Heat-Shock Proteins - biosynthesis; Heat-Shock Proteins - chemistry; Hot Temperature; immunocytochemistry; L cells; light; light intensity; Luminous intensity; Membrane Proteins - analysis; Membrane Proteins - biosynthesis; Metabolism; Microscopy, Electron; Mitochondria; Mitochondria - metabolism; Mitochondria - ultrastructure; Molecular Sequence Data; Molecular Weight; Nitrogen metabolism; Plant cells; Plant physiology and development; Plant Proteins - analysis; Plant Proteins - biosynthesis; Plants; Plants - metabolism; Plastids; Plastids - metabolism; Plastids - ultrastructure; Protein Biosynthesis; Proteins; regulation; Sequence Homology, Amino Acid; Shock; stress; Transcription, Genetic; Western blotting; Intracellular transport; Gene expression; Chenopodiaceae; Luminous intensity; Mitochondria; Regulation(control); Polypeptide; Dicotyledones; Angiospermae; Heat shock protein; Spermatophyta; Localization; Chenopodium rubrum
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250050074

The 23-kDa nuclear-encoded heat-shock protein (HSP) of Chenopodium rubrum L. is regulated by light at the posttranslational level. Higher light intensities are more effective in inducing the accumulation of the mature protein under heat-shock conditions. Based on this and other properties the protein was considered to belong to the group of small chloroplastic HSPs. However, we have now obtained the following evidence that this 93-kDa HSP is localized in the mitochondria: (i) Immunogold-labelled protein was almost exclusively restricted to the mitochondria in electron microscope thin sections. (ii) Using purified, isolated mitochondria from potato tubers the in-vitro-synthesized translation product of 31 kDa was readily transported into mitochondria where it was processed to the 73-kDa product. (iii) The protein could be detected by Western blotting in a preparation of washed mitochondria of Chenopodium, while under the same conditions no signal could be obtained in a preparation of isolated chloroplasts. (iv) Finally, sequence comparison with the published sequences of mitochondrial proteins by Lenne et al. (1995, Biochem J 311:805-813) and LaFayette et al. (1996, Plant Mol Biol 30:159-169) showed clearly that the 23-kDa protein is considerably more similar to these two proteins than to the group of plastic small HSPs. From these data we infer that mitochondria are involved in the response of the plants to high light stress under heat-shock conditions.