Abstract
We have identified and characterized a homolog of the 40 kDa cyclophilins in the budding yeast Saccharomyces cerevisiae. At the amino acid level, this novel yeast cyclophilin, termed Cyp40, is 47% identical to human cyclophilin-40. Recombinant Cyp40 produced in bacteria has a peptidyl-prolyl cis-trans isomerase activity with a catalytic efficiency (k[cat]/K[m]) of 0.5 x 10(6)M(-1)s(-1), which can be inhibited by cyclosporin A with an IC50 value of 60nM. Using a polyclonal antibody against Cyp40 we have found that Cyp40 is predominantly cytoplasmic, and that its expression is induced 3-4-fold by heat shock. Moreover, Cyp40 can be coprecipitated from yeast extracts with the cytosolic molecular chaperone Hsp90. Surprisingly, a Cyp40-deficient yeast strain is fully viable at normal and elevated temperatures. Cyp40 is also dispensable for normal regulation of vertebrate steroid receptors in yeast. While other immunophilins could conceivably compensate a Cyp40 defect, our results are compatible with the notion that immunophilins may be fortuitous partners in the biochemically established steroid receptor-Hsp90 complex.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Amino Acid Isomerases / chemistry
-
Amino Acid Isomerases / genetics
-
Amino Acid Isomerases / physiology*
-
Amino Acid Sequence
-
Base Sequence
-
Binding Sites
-
Carrier Proteins / chemistry
-
Carrier Proteins / genetics
-
Carrier Proteins / physiology*
-
Chromatography, Affinity
-
Cloning, Molecular
-
Cyclosporine / pharmacology
-
Cytoplasm / enzymology
-
Endodeoxyribonucleases / chemistry
-
Endodeoxyribonucleases / genetics
-
Endodeoxyribonucleases / physiology*
-
Fungal Proteins / metabolism
-
HSP90 Heat-Shock Proteins
-
Heat-Shock Proteins / metabolism
-
Humans
-
Immunosuppressive Agents / pharmacology
-
Molecular Sequence Data
-
Molecular Weight
-
Peptidylprolyl Isomerase
-
Receptors, Steroid / physiology*
-
Recombinant Proteins / metabolism
-
Saccharomyces cerevisiae / enzymology*
-
Saccharomyces cerevisiae / genetics
-
Saccharomyces cerevisiae Proteins
-
Stereoisomerism
-
beta-Galactosidase / metabolism
Substances
-
Carrier Proteins
-
Fungal Proteins
-
HSP82 protein, S cerevisiae
-
HSP90 Heat-Shock Proteins
-
Heat-Shock Proteins
-
Immunosuppressive Agents
-
Receptors, Steroid
-
Recombinant Proteins
-
Saccharomyces cerevisiae Proteins
-
Cyclosporine
-
Endodeoxyribonucleases
-
beta-Galactosidase
-
Amino Acid Isomerases
-
Peptidylprolyl Isomerase
Associated data
-
GENBANK/U48867
-
GENBANK/U48868