Poster: Temperature Responses
Abs #
202: Plant hsp90 chaperone system: the p23 surprise!
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Presenter: |
Krishna, Priti , pkrishna@uwo.ca |
Authors | Krishna, Priti (A) Zhang, Zhongming (A) | | Affiliations: |
(A): Department of Biology, University of Western Ontario
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Hsp90 is a unique molecular chaperone that plays a key role in signal transduction networks. It has been proposed as a capacitor for morphological evolution, and is emerging as a promising drug target. The study of hsp90 complexes, in particular those involving animal steroid receptors, has revealed that hsp90 promotes folding and activation of its client proteins in cooperation with a number of cochaperones. The hsp90-based chaperone complex contains hsp90, Hop, hsp70, hsp40, a high Mr immunophilin, and p23. An additional component p50/Cdc37 has been detected in hsp90 complexes with protein kinases. The hsp90 family of proteins is largest in plants, but despite the availability of hsp90 genes from a variety of plants our knowledge of hsp90 in plants remains limited. Plant hsp90 gene products, their client proteins, the hsp90 chaperone complex(es) as well as hsp90 mode of action, are likely to encompass unique features that will present novel opportunities. We have identified and partially defined an hsp90-based chaperone system in plants. The components identified to date include hsp90, hsp70, a Hop homolog, and the immunophilins. A p23-like activity was not detected in wheat germ lysate. This, together with other observations, led to the belief that a p23 homolog is not present in plants. Here we report the first biochemical demonstration of a plant p23 homolog, discuss its novel characteristics, and explain why it had escaped detection. We also demonstrate that while animal p23 can interact with plant hsp90 in vitro, a complex between these proteins could not be detected in extracts of plants expressing p23 of animal origin. In addition, there will be comparative discussion of the similarities and differences between the plant and animal hsp90 chaperone complex.
