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Hsp90-containing multiprotein complexes in the eukaryotic microbe Achlya
S A Brunt1, G H Perdew, D O Toft
1Department of Medical Genetics and Microbiology, University of Toronto, Scarborough Campus, Ontario, Canada.
Cell Stress & Chaperones
|May 19, 1998
Summary
Researchers identified heat shock protein 70 (Hsp70) and other proteins in the oomycete Achlya ambisexualis, revealing similarities and unique components in its Hsp90-heterocomplexes compared to vertebrates.
Area of Science:
- Molecular Biology
- Mycology
- Biochemistry
Background:
- The steroid hormone antheridiol induces sexual differentiation in the oomycete fungus Achlya ambisexualis.
- Antheridiol binds to a 9S multiprotein complex in A. ambisexualis cytosols, which contains heat shock protein 90 (Hsp90).
- The full composition of these Achlya Hsp90-heterocomplexes and their homology to vertebrate steroid receptor complexes were previously unknown.
Purpose of the Study:
- To identify the protein components of the Achlya ambisexualis Hsp90-heterocomplexes.
- To investigate potential homologies between Achlya Hsp90-heterocomplex components and those found in vertebrate steroid receptor complexes.
Main Methods:
- Co-immunoprecipitation assays were used to identify proteins that associate with Achlya Hsp90.
- Proteins were characterized based on their molecular weight (kDa).
- Specific protein identifications were confirmed using techniques like relating to known vertebrate proteins and analyzing in vitro translates.
Main Results:
- Multiple cytosolic proteins (110, 74, 64, 61, 56, 47, 27, and 23 kDa) co-immunoprecipitated with Achlya Hsp90.
- The 74 kDa protein was identified as heat shock protein 70 (Hsp70).
- The 23 kDa protein showed homology to vertebrate p23, and the 56 kDa protein to immunophilin FKBP51, both known components of vertebrate steroid receptor complexes.
- Proteins of 110, 61, and 27 kDa appeared unique to Achlya. The 61 kDa protein was specifically found in complexes from antheridiol-treated mycelia.
Conclusions:
- Achlya ambisexualis Hsp90-heterocomplexes contain Hsp70, a p23-related protein, and an FKBP51-related protein, sharing some components with vertebrate steroid receptor complexes.
- The presence of unique proteins, including one induced by antheridiol, suggests distinct regulatory mechanisms in Achlya sexual differentiation.
- These findings provide insights into the evolution and composition of Hsp90-dependent signaling complexes across different eukaryotic kingdoms.