Plant organelles contain distinct peptidylprolyl cis,trans-isomerases.
Peptidylprolyl cis,trans-isomerase (PPIase) activity was detected in the cytosol, mitochondria, and chloroplast of pea plants. Cyclosporin A inhibited the activity largely localized to the mitochondrial matrix while rapamycin inhibited the PPIase activity associated with the mitochondrial membranes. Differential inhibition by the two immunosuppressive drugs, the specific binding of these drugs to different mitochondrial fractions, and the immunological detection of a putative 25-kDa rapamycin-binding protein (RBP) in mitochondrial extracts attests to the presence in plant mitochondria of both cyclophilin and RBP classes of PPIases. Cyclosporin A-sensitive PPIase detected in the chloroplast was mostly localized to the thylakoids, which is suggestive of its function in the folding of membranal proteins. PPIase associated with the chloroplast stroma and the thylakoids was not inhibited by rapamycin nor was any cross-reactive RBP detected in chloroplast extracts. These results demonstrate the presence of distinct classes of PPIases in the mitochondria and the chloroplasts of plants.
Breiman
A
A
Plant Molecular Biology Laboratory, Beltsville Agricultural Research Center-West, Maryland 20705-2350.
Fawcett
T W
TW
Ghirardi
M L
ML
Mattoo
A K
AK
D000591:Amino Acid Isomerases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology*; D002852:Chromatography, Ion Exchange; D003429:Cross Reactions; D016572:Cyclosporine / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000201:enzymology*; D006360:Heat-Shock Proteins / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D019696:Peptidylprolyl Isomerase; D010946:Plants, Medicinal; D022021:Tacrolimus Binding Proteins
D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D016572:Cyclosporine; D000591:Amino Acid Isomerases; D022021:Tacrolimus Binding Proteins; D019696:Peptidylprolyl Isomerase