Journal Article

Subcellular Localization and Targeting of Glucocorticoid Receptor Protein Fusions Expressed in Transgenic <i>Arabidopsis thaliana</i>

Barbara Brockmann, Maria W. Smith, Andrey G. Zaraisky, Kate Harrison, Kazunori Okada and Yuji Kamiya

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 9, pages 942-951
Published in print September 2001 | ISSN: 0032-0781
Published online September 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce120
Subcellular Localization and Targeting of Glucocorticoid Receptor
Protein Fusions Expressed in Transgenic Arabidopsis thaliana

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  • Biochemistry
  • Molecular and Cell Biology
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An animal system of inducible activation of protein fusions with the binding domain of glucocorticoid receptor (BDGR) was tested in Arabidopsis thaliana by monitoring dexamethasone (DEX)-induced nuclear targeting of reporter constructs. Two constructs containing green fluorescent protein (GFP), human homeobox protein Hanf-1 and Xenopus laevis BDGR were used, GFP/Hanf-1/BDGR and GFP/BDGR. The control construct contained GFP alone. In the absence of DEX both fusion proteins were uniformly distributed in the cytoplasm of root cells, but showed strong association with plastids in plant aerial parts. DEX treatment of roots prompted a strong and reversible nuclear accumulation of GFP/Hanf-1/BDGR, but not GFP/BDGR. Thus, in roots, the specific nuclear translocation of GFP/Hanf-1/BDGR was driven by Hanf-1 and tightly regulated by BDGR. However, in plant aerial parts treated with DEX, nuclear translocation of GFP/Hanf-1/BDGR was observed only in a few cases, and most part of the fusion protein was incorrectly and irreversibly targeted to plastids. Protease X digestion of isolated chloroplasts showed that BDGR fusion proteins were translocated into the chloroplast envelope and bound to envelope membranes, probably due to association with the chloroplast import apparatus. Thus, for efficient use of the glucocorticoid-inducible system in plants, it will be necessary to modify BDGR structure to prevent incorrect targeting of fusion proteins.

Keywords: Key words: Arabidopsis — Dexamethasone — Fusion protein — Glucocorticoid — Hanf-1 — Targeting.; Abbreviations: BD, binding domain; DEX, dexamethasone; DAPI, 4,6-diamidino-2-phenylindole; GFP, green fluorescent protein; GR, glucocorticoid receptor; HSP, heat shock protein.

Journal Article.  6613 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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