&cestflwr; The Hsp90 family of proteins in Arabidopsis thaliana

Abstract

The 90-kDa heat shock protein (Hsp90) is an essential molecular chaperone in eukaryotic cells, with key roles in the folding and activation of proteins involved in signal transduction and control of the cell cycle. A search for Hsp90 sequences in the Arabidopsis thaliana genome revealed that this family includes 7 members. The AtHsp90-1 through AtHsp90-4 proteins constitute the cytoplasmic subfamily, whereas the AtHsp90-5, AtHsp90-6, and AtHsp90-7 proteins are predicted to be within the plastidial, mitochondrial, and endoplasmic reticulum compartments, respectively. The deduced amino acid sequences of each of the cytoplasmic proteins contains the highly conserved C-terminal pentapeptide MEEVD. All of the AtHsp90 sequences include a conserved adenosine triphosphate-binding domain, whereas only the cytoplasmic and endoplasmic reticulum-resident sequences include an adjacent charged linker domain that is common in mammalian and yeast sequences. The occurrence of multiple AtHsp90 proteins in the cytoplasm and of family members in other subcellular compartments suggests a range of specific functions and target polypeptides.

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

“…CAB78329) was identi®ed by database search in this study. Our search results are in agreement with the ®ndings of Krishna and Gloor (2001). HSP88.1 and HSP89.1 were identi®ed through screening a genomic library using a carrot HSP90 cDNA (Milioni and Hatzopoulos, 1997).…”

Molecular Chaperone Hsp90 Associates with Resistance Protein N and Its Signaling Proteins SGT1 and Rar1 to Modulate an Innate Immune Response in Plants

“…Silencing of NbHsp90-1 using VIGS vectors carrying fragments of NbHsp90-1 sequence resulted in severe plant developmental defects and ultimately in plant death. In Arabidopsis, there are four Hsp90 homologs (20) that show high homology to NbHsp90-1 (Fig. 1).…”

“…1). NbHsp90-1 and -2 possess the C-terminal MEEVD pentapeptide that is characteristic of cytoplasmic Hsp90 proteins (20). Comparison of the amino acid sequences of these proteins with Arabidopsis and human cytoplasmic Hsp90 proteins revealed very high homology (Fig.…”

Does an expressed sequence tag (EST) library ofSalsola iberica(tumbleweed) help to understand plant responses to environmental stresses?

“…16 Two transcripts from our S. iberica analysis closely matched HSP90 (E-value = 1.16 E-116), which is involved in stabilizing cellular proteins upon stress conditions. Koning et al 20 performed a northern blot and a GUS assay of a transgenic Arabidopsis line and showed that HSP80 is upregulated in development.…”